THE GENUS In the West Bank and Gaza Strip

by

DR. MOHAMMED S. ALl - SHr A YEH

Department of Biological Sciences An - Najah National University

Published by Research and Documentation Centre An- ajah National University - Nablus 1986 ,I.'

Copyright © 1986 by The Resarch and Documentation Centre, An': Najah National University, Nablus PREFACE This monograph is aimed at providing a well illustrated guide to the species of Pythium in the West Bank and Gaza Strip. A key for all the species recovered is given. However, the reader is advised to always check through the description given to the species to make sure that he has made the right identification. This description has been based on several freshly recovered isolates that came from different habitats in order to account for inter and intraspecific variations. A guide to the isolation methods is also provided. Also, information on the distribution and host range of the different species is given. I believe that we still have a lot to learn about this important group of fungi especially with respect to their physiology, genetics, and taxonomy. However, this book has covered fundamental topics on the genus Pythium and that it would be particularly useful to students of mycology, botany, plant pathology, ecology, and biology

ACKNOWLEDGNENTS

I would like to exprees my gratitude to a number of people who directly or indirectly helped in the preparation of this monograph. I am in the first place indebted to the Dea n of the Research and Documentation Centre for allowing the publication of this book. I also wish to express special thanks to my research students, laboratory technicians, and research assistants at the Department of Biological Sciences, and friends who have offered help and encouragement when I most needed it. Lastly but no means least I acknowledge the financial support donated generously by the Department of Biological Sciences throughout this work. CONTENTS Summary 1

J. Introduction 2-4 II. Materials and Methods 5-9

III. Key to Pythium spp isolated in the West Bank and Gaza Strip. 10 - 15 I V. Desceiptions of species 16 - 66 V. Host list 67 - 68 V I. References 69 -74 VII. Index of fungal names. 75 - 76 VIII. Arabic abstract. 78 SUMMARY

A key to the 48 taxa of Pythium recorded so far from the West Bank and Gaza Strip is given.isolation and preservation methods are also provided. The following species are described and illustrated: P. acanthicum Drechsler, P. anandrum Drechsler, P. aphanidermatum (Edson) Fitzp, P. coloratum Vaartaja, P. conidiophorum loki, P. debaryanum auct non Hesse, P. dissimile Vaartaja, P. dissotocum Drechsler, P. echinulatum Matthews, P. graminicola Subramaniam, P. intermedium de Bary, P. irregulare Buisman, P. iwayamqi S. Ita, P. mamillatum Meurs, P. middletonii Sparrow, P. monospermum Pringsh, P. nagaii S. Ita & Tokunga, P. oligandrum Drechsler, P. papillatum Matthews, P. paroecandrum Drechsler, P. pulchrum Minden, P. rostratum Butler, P. salpingophorum Drechsler, P. spinosum Sawada, P. splendens Braum, P. sylvaticum Campbell & Hendrix, P. torulosurn Coker & Patterson, P. ultimum var sporangiiferum Drechsler, P. ultimum Trow var ultimum, P. vantrepoolii V. Kouyeas, and P. vexans de Bary. Descriptions were produced from the study of several isolates in order to account for intraspecific variation. The other 17 taxa were outlined briefly. These taxa were isolated only once or twice and/ or failed to from sexual reproductive structures following their identification (P. deliense Meurs, P. dimorphum Hendrix & Campbell, P. hypogynum Middelton, P. myriotylum Drechsler, P. orthogonon Ahrens, P. periplocum Drechsler, P. pyrilobum Vaartaja, and P. tracheiphilum Matta), taxa without oogonia (P. group 'F', P. group 'G', P. group 'HS', and P. group 'L'), and taxa described by the author in 1982 from Britain (P. lucens, P. lutarium, p. minor, p. pachycaule, and P. parvum) and were also isolated from the West Bank. Occurence of the different taxa in the West Bank and Gaza Strip as well as in other neighbouring countries is briefly outlined. All known records of rare species are mentioned. All known host records of Pythium from the West Bank and Gaza Strip are also listed. I. INTRODUCTION The genus Pythium is now regarded as the type genus of the family Schroter in the order of the class Ooomycetes (Waterhouse, 1973; Plaats-Niterink, 1981). The genus was introduced by Pringsheim (1858). His genus was based on two fungi, Pythium monospermum and P. entophytum. The latter fungus was transferred to Lagenidium (Zopf, 1890), so that P. monospermum remained as the type species. Pringsheim (1858) placed Pythium in the Saprolegniaceae, but de Bary (1881) placed the genus in the Peronosporaceae. Schroter (1897) created the family Pythiaceae for the genera Pythium and Nematosporangium. Butler (1907) did not accept Nematosporangium as representing a distinct group of species, so he included all the species under Pythium. Monographs on the genus have been published by Butler (1907), Matthews (1931), Sideris (1931, 1932), Middelton (1943), and Frezzi (1956). Waterhouse (1967, 1968) compiled the original descriptions and illustrations of all Pythium taxa described at that time; a total of )79 taxa. She produced a key for eighty nine taxa which she considered as .valid and rejected ninety taxa. This key depended heavilly on the original descriptions of the species. Since many of these were produced from the study of single isolates, without taking into consideration the possible sources or ranges of variation, original descriptions were often inadequate for comparative purposes. As a result the key frequently has to depend upon small differences in reproductive cell-size; it also emphasizes some nonmorphological characters. Robertson (1980) produced a key to the twenty seven species of Pythium recorded so far from New Zealand; illustrations and descriptions were given for sixteen species. Plaats-Niterink (1981) published the latest monograph of the genus Pythium. She recognised and described eighty five species, seven of which are heterothallic. Descriptions were again based on single isolates. Therefore, extent of intraspecific variation was not accounted for in both Robertson and Plaats-Niterink keys. However, it is difficult to assess intraspecific variation from published descriptions since the majority of these were prepared from single isolates. Pythium species occupy a wide diversity of habitats. They can be found as saprobes in fresh and salt water and in soil, and as parasites in aquatic and terrestrial plant material, fresh water and marine algae, fungi, invertebrates and vertebrates (Middleton, 1943; Plaats-Niterink, 1981). Species of Pythium have been often referred to as 'sugar fungi' (Garret, 1951; Burges, 1958), a term which infers their inability to degrade complex carbohydrate polymers, like cellulose. However, it has been recently found that several species of Pythium are capable of degrading cellulose (Taylor & Marsh, 1963; Tribe, 1966; Willoughby & Redhead, 1973; Park, 1980 a,b; Deacon, 1979). It has been therefore suggested (Deacon, 1979) that the cellulolytic activity of Pythium species removes these fungi from the substrate group 'sugar fungi'.

2 Pythium species such as P. periplocum, and P. acanthicum have been reported as mycoparasites on both other species of Pythium such as P. ultimum, P. debaryanum, P. irregulare and P. salpingophorum (Haskins, 1963; Deacon, 1976; Vesely, 1978; Deacon & Henry, 1978) and other fungi such as Fusarium roseum (Deacon & Hery, 1978). Pythium oligandrum was found by Deacon (1976) to be an efficient mycoparasite of Rhizoctonia solani, Fusarium culmorum and a Trichoderma species and the possibility of using this fungus in bilogical control of damping-off diseases has been considered (Deacon, 1976; Vesely, 1978).

Pythium species have also been reported from nests, intestines, feathers of free living birds in Czechoslovakia and Yugoslavia (Hubalek, 1974 a,b), and droppings of birds previousely fed with these fungi (Thornton, 197 I). Pythium species have also been recorded from fish (Scott & O'Bien, 1962), Daphnia and Bosmina (Peterson, 19lOj Plaats-Niterink, 1972, 1975), and crustacean eggs and mosquito larvae (Stanghellini, 1974). The extent of pathogenicity to animals is not known. Austwick & Copland (1974) found that Hyphomyces destruens-equi which might be a Pythium species, is probably pathogenic to horses. Pythium spp are distributed worldwide (Tompkins, 1975; Domsch et ai., 1980; Plaats- Niterink, 1981). Some species such as P. ultimum, P. rostratum, and P. irregulare have appeared consistently in the lists derived from the majority of the reports in the literature (Vaartaja, 1968; Hendrix & Campbell, 1970; Plaats- Niterink, 1975; Robertson, 1980; Ali, 1982, 1985). On the other hand other species such as Pythium deliense, P. aphanidermatum and P. myriotylum have a high temperature optimum and are apparently restricted in distribution and economic range to warm climates (Garren, 1970; McCarter & Littrell, 1970; Ali, 1985).Of the.eighty five species recognized by Plaats-Niterink (1981) more than sixty species are either known only from original description or have been recorded so seldom that comments on their distribution are impossible.

Many Pythium species are soil inhabitants, living saprophytically or parasitically (Stanghellini, 1974; Domsch et al., 1980; Ali, 1982) Some Pythium species are among the most destructive plant pathogens (Agrios, 1978). Their pathogenic capacity is largely determined by the availability of pectolytic and cellulolytic enzymes. Phytotoxins and indolic growth factors have also been isolated from a number of species (Blok, 1973). The majority of Pythium species are capable of parasitising seeds, seedlings, and older stages of a wide range of plants (Robertson, 1980) causing damping-off disease. However, the greatest damage is done to the seeds and the roots of seedlings either before or after emergence (Agrios, 1978). Their role as plant pathogens depends on several factors, including density of potential inoculm (of which inoculm potential is a function, Dick,1981), soil water content, soil temperature and pH, competition of other microorganisms-and cation content (Hendrix & Campbell, 1973; Plaats- Niterink, 1981).

3 Little is known about the distribution of population of Pythium species in soil either on a global or on a local basis, particularly in quantitative terms. The introduction of selective media has enabled estimates of propagule numbers to be made. Pvthium population under in Georgia (U.S.A.) were determined by Otrosina and Marx (1975) who found means for numbers of propagules from all sites to range from 0-5.2 propagules.g dry wt-I over all seasons; isolates corresponding to the Pythium irregulare-P. debaryanum complex were most frequently isolated. Lumsden et al. (1976) and Pieczarka & Abawi (1978) studied Pythium species population in bean fields in Maryland and New York respectiverly, and found Pythium isolates with spherical sporangia and which did not produce oogonia and P. uftimum to be most frequent.

Pythium population in forest nursery soils in Australia and Canada and in the south eastern United States were studied by Vaartaja (1964,1968) and Hendrix & Campbell (1968) respectively. They found P. irregulare to be the most abundant species. The distribution of Pythium were studied by Hendrix & Campbell (1970) in different soils from many parts of the USA. Heterothallic forms together with isolates referable as P. irregulare- P. debaryanum complex, were found to dominate Pythium flora in the soils studied. Twenty eight to thirty five years ago,Remy (1950), Warcup (1952) and Barton (1958)all concluded that Pythium species were abundant in cultivated soils but infrequent in uncultivated, undisturbed soils. However their conclusions were based on recovery techniques which are known to be less satisfactory for quantitative studies, thus making direct comparisons of population levels impossible. Using a selective medium (VP3) and the surface-soil-dilution-plate procedure, Ali (1982), Ali-Shtayeh et af (l986a,b), Ali-Shtayeh & Dick (1986); and Dick & Ali-Shtayeh (1986) studied Pythium populations in a large number of cultivated and uncultivated soils in Britian and found Pythium species to be more abundant in cultivated farmland soils than in undisturbed, uncultivated parkland soils. Species widely distributed in uncultivated soils were P. sylvaticum, P. rostratum, P. parvum, and P. acanthicum .. The abundant and widespread species in cultivated farmland soils were P. minor, P. parvum, P. rostratum and P. vanrerpoolii.

Pythium populations in a wide range of irrigated and nonirrigated fields in the West Bank and Gaza Strip have been studied by the author. A part of this work has now been published (Ali, 1985, Ali-Shtayeh, 1985,1986 a,b). In this monograph a guide to the isolation and identification of Pythium species is provided. Descriptions are also provided for 31 species. The remaining species isolated from the West Bank and Gaza Strip are outlined briefly. All the plants from which Pvthium species have been recovdred are listed.

4 II. MATERIALS AND METHODS ISOLA TION TECHNIQllrs A. Isolationjrom soil: a. Use of Selective media and soil dilution technique:

I. Collection ofsamples: From each site (from 45 fields) four soil samples each approximately 250 g fresh weight were taken with a trowel from an area of approximately 4m2 at a depth of 0-1 Ocm (Picczark a & Abawi. 1978). The four samples were put into a plastic bag.

2. Prepartion of soil suspensions: Soil suspensions in 0.09% sterile water agar were made from each composite sample using 50g soil aliquots. Soil dilutions of 1:50; I: 100; 1:250; 1:500; were used depending on anticipated population densities in the soils sampled CAli, 1985a) 3. Selective medium and the surface-soil-dilution plating: Plates of VP3 medium, prepated within the previous 36h, were incoulated by pipetting a I em' aliquot of the soil dilution onto the surface. The aliquot was spread over the surface of the plate using a sterile, bent glass rod, and the plate rotated by hand to give an even spread. The VP3 medium was prepared as follows: Sucrose, 20g; MgS04. 7H20, IOmg; ZnCI2, I mg; FeS04. 7H20, 0.02mg; Mo03, 0.02mg; CuS04. 5H20, O.02mg; thiamine hydrochloride, 100).1gcorn meal agar (C:MA), 17g; Oxoid No. I agar, 23g, made up to 990 ml with demineralized water and autoclaved. Vancomycin 75mg; PCNB, 100mg; penicillin 50000 units; pimaricin, 5mg, and rose bengal 2.5mg were mixed in 5ml sterile destilled water and added, with a further Sml of rinsings of a sterile disilled water. to the agar when it had cooled to SO-Ssoc. After addition, mixing was achieved by thorough rotation of the 2L flask by hand before bouring onto the plates. When the medium in the plates had solidified, the plates were stored in the dark because pimaricin is sensitive to light (Schmitt henner, 1973).

4.1ncubation and detection of Pythium colonies: Inoculated plates were incubated at 22-2So C for 24-48hr and examined for the presence of Pythium species. SOil particles, bacterial contaminants and Mortierella spp were removed from the surface of isolation plates by washing the agar surface under tap water. b. Baiting technique:

Several kinds of baits were used for the isolation of Pythium species from soil and aquatic habitates. Sterilized plant parts such as apples twigs, and leaves were used. Autoclaved corn kernels and lupin seeds were also frequently employed. Animal material such as flies. Drosophil a and snake skin were also used as baits. Paper squares pre-soaked in Richard's solution (Ali, 1982, CM1, 1983) containing 5 mgjL pimaricin were also found to be effective in trapping Pythium spp from soil and water.

5 B. Isolation of Pythium spp from infected plant parts: Pythium spp were isolated from infected plant tissue by plating on the VP3 medium plates or on plates of 2% water agar containing 5 mg( L pimarinin. Excised plant material was first washed under running tap water for about 2 hours, surface-sterilised in 0.5% sodium hypchlorite for 3 miniutes, rinsed in sterile distilled water, blotted dry on sterile filter paper, and then plated on the agar plates. The plates were then incubated at 22-250 C for 24-48 hours and examined for the presence of Pythium colonies.

MAINTENANCE OF STOCK CULTURES Stock cultures of representative isolates of Pythium species studied were maintained either in water culture in 100mi conical flasks (Dick, 1965), or on CMA slants (Robertson, 1980; Plaats-Niterink., 1981) in 100mi universal bottles. All the stock cultures were kept at 100e. IDENTIFICA TION OF PYTHIUM SPECIES Transfer of colonies from rough cultures: Small excisions from growing margin of Pythium colonies. on the isolation plates or on rinsed baits were cut off and either transferred directly to water culture with 1-2 autoclaved corn kernels per dish, or to corn meal agar (CMA) or 2% water agar plates, and then transferred into water culture after they had been incubated for 24-48h at 220 C. Representative isolates of the isolated species (3 of each) are maintained at the Fungal Culture Collection of An-Najah University (Ali-Shtayeh, 1986b). Induction of sporangial and zoospore formation: For production of sporangia and zoospores, dishes were half-filled with sterile distilled water (OW) or with an autoclaved mixture of one part filtered pond water and two parts distilled water (DDW). Two grass blades (Emerson, 1958), boiled for IS minutes, were then placed on or near the hyphal tips. Coloized grass blades were then transferred to new dishes half-filled with water (OW or OOW as appropriate), incubated for 24-48 h at 10-22° C, rinsed daily with water from the same source, and examined periodically for 2-7 days for zoosporangia . If zoospores were not produced at these temperatures, cultures were put in a refrigerator at 2-50 C for 1-2 h before they were examined for zoospore production. Changing the water and chilling the cultures may enhance both the production of sporangia and the discharge of zoospores (Ali, 1982).

Induction of sexual structures formation: For production of sexual structures similar blocks of agar containing hyphal tips were flooded with OW. Two boiled corn kernels were placed adjacant to the hyphal tips and cultures were then incubated at 220 C for 7-14 days before they were examined. When oogonia were not produced in water culture, isolates were grown on Schmitthenner's medium (Schmitthenner, 1962) or on CMA supplemented with wheat germ oil (500 mg( L) to provide sterols needed for sexual reproduction (Hendrix & Papa, 1974). Schmitthenner's medium and CMA supplemented with wheat germ oil were found to be satisfactory for oogonial production and microscopic examination was easy because of the clear substrate. 6 Microscopic examination: Microscopic examinations were made on living material, either under the low power (X 10) on undisturbed water culture, or under high powers (X45, X60, X 100, using water mounts ringed with nail varnish. Occasionally material fixed and stained in lactophenol cotton blue was also used. Taxonomic characteristics observed: When Pythium isolates were examined microscopically the following characteristics were taken into account: I. Sporangia, sporangial shape (filamentous, toruloid or lobulated, globose or sublobose), details of sporangial papilla; sporangial location (terminal, intercalary, catenulate or noncatenulate); sporangial dimensions; and subsequent developent (proliferation, deciduousness, production of zoospores, evidence of direct germination). 2. Hyphal swellings, their morphology, dimensions, location and germination). 3. Oogonia, oogonial wall (smooth or spiny, regular or irregular); oogonial dimension; oogonial location (terminal or intercalary). 4. Antheridia, number per oogonium; origin (monoclinous, diclinous, hypogynous, intercalary); application (lateral, terminal); stalk (including length of stalk and distance of origin from basal septum of oogonium); shape (club- shaped, bell-shaped, elongate, round or inflated); branching of antheridial stalk; contact interface with oogonia (broad, narrow). 5. Oospore, oospore wall (smooth or reticulate, thickness, colour) wether it filled (plerotic) or did not fill (aplerotic) the oogonial cavity; appearance of the ooplast; number of oospores per oogonium; oospore dimensions. 6. Mycelium (septation, branching, swellings), and appressorial development in agar cultures. 7. Colony morphology, growth form and mycelial density on the agar plates; aerial mycelium. (see Fig I.) Measurements and observations on the above-mentioned morphological features of representative isolates of Pythium recovered from the West Bank and Gaza Strip from 1982-1985 were recorded on measurement data sheets prepared for this purpose. All measurements were taken using an ocular micrometer and an oil immersion lens xIOO. Biometric data were collected for hyphal diameter, sporangia or hyphal swellin~s, oogonia, spines, oospores, oospore wall and reserve globules. Means and 95% confidence intervals were calculated. Statistical checks were made initially to verify that twenty five structures were sufficient to characterize the population.

7 f-ig. I. (ll()n~ morphllIU!!\' (It Pv tluuru srI' on eM A at 2)!'C. (A) Y lutarium, 11<1'pc',i.li ;':III;JI1 (HI P. minor "lWli,' puucrn, (e)P. puchvcaule, indistinct "",,:lll' puucrn \\Ili, ';iI),d,1 dcv clopmc nt 01" aerial mycelium. (OJ? lucens. ind 1,1 inct ei1ry,al he 111urn pattern. (E) P. I'IJ.I'I ra I urn , chrysanthemum pattern, (F) P. parvum radiate patten

8 Growth rate and temperature limits of Pythium spp: To determine temperature- growth relationships of Pythium species, representative isolates were grown on CMA for 24 h at 0,5,10,15,20,25,30,35,37, and 420 C. Plates were inoculated with 5-mm discs of inoculum and then incubated at the above range of temperatures. Three replicate plates were used for each temperature aRd average linear growth of each isolate was calculated.

9 III. KEY TO PYTHIUM SPP. ISOLATED IN THE WEST BANK AND GAZA STRIP. Living isolates of the species so far reported from the West Bank and Gaza Strip were examined. Illustrated descriptions are given for those marked (*) in the key. The other species included in the key are noted briefly.

Oogonia and antheridia produced in single 2 cultures Oogonia and antheridida not or scarcely produced in single cultures 47

2(1) Oogonial wall smooth or occasionally with few projections 3 Oogonial wall ornamented with spines 17

SPECIES WITH SMOOTH OOGONIA

3(2) Sporangia filamentous, inflated or not 4 Sporangia globose or subglobose, proliferating or not (sometimes only hyphal swellings present) 25

4(3) Sporangia not or slightly inflated 5 Sporangia inflated, lobulated or toruloid 9

SPORANGIA FILAMENTOUS, NOT OR SLIGHTLY INFLATED

5(4) Oospores plerotic 6 Oospores aplerotic 8

6(5) Oogonia usually with 1-3 papillae, 15.3± 0.4 -95% c.1. urn diam; antheridia usually lacking P. papillatum* Oogonia smooth; antheridia present 7

7(6) Oogonia 21.6± 0.7)Jm diam; antheridia diclinous, sometimes branched; hyphal swellings occasionally present P.lutarium Oogonium l7.2± 0.6-95% c.1. urn diam; antheridia monoclinous and diclinous, not branched; hyphal swellings absent P. monospermum*

8(5) Oogonia 26.6± 1.4-95% urn diam, when elongated then 44-110 urn long, globose, sac shaped or trumpetshaped, usually with a long thick neck-cell P. pachycaule Oogonia 19.7± 0.8-95% c.1..um diam, globose or pyriform, thick neck-cells absent P. coloratum*

10 SPORANGIA FILAMETOUS, INFLATED 9(4) Antheridia absent or rare and then hypogynous P. dissimile* Antheridia present 10

10(9) Oogonia smooth II Oogonia spiny P. periplocum

11(10) Oospores aplerotic 12 Oospores plerotic 15

12(11) Antheridia usually intercalary 13 Antheridia usually not intercalary 14

13(12) Oogonial stalk typically curved towards antheridia P.deliense Oogonia stalk straight P. aphanidermatum"

14(12) Sporangia consisting of inflated toruloid parts and discrete globose elements P. pyrilobum Sporangia consisting of inflated lobulate elements; discrete globose sporangia absent P. myriotylum

15(11) Oogonia 26.1± 1.3-95% C.I urn diam, antheridia up to 6/ oogonium P. graminicolum Oogonia smaller, 20)Jm diam ill average; antheridia up to 3/ oogonium 16

16(15) Oogonia 18.8± 0.6-95% C.Lum diam; antheridial stalks originating 15-25 .um below oogonium, oospore wall thick, 2-4 ..urn thick P. vanterpoolii* Oogonia 15.6± 0.5-95% C.I..um diam; antheridial stalks originating at a distance of 1-2..umfrom the oogonium, oospore wall thinner 1-2..um thick P. torulosum*

SPECIES WITH ORNAMENTED OOGONIA 17(2) Sporangia unknown, hyphal swellings present, oogonial prejections cylindrical; antheridia 1- 3/ oogonium, usually monocIinous P. spinosum" Sporangia present 18

18(17) Sporangia filamentous or toruloid lY Sporangia globose, oval, ellipsoidal or elongated 20

11 19( 18) Sporangia not inflated; antheridia usually absent rarely present and then monoclinous; oogonial projectiuns few, blunt P. papillatum* Sporangia inflated; antheridia present; oogonial projections numerous, blunt P. periplocum

20(18) Sporangia consisting of irregular subglobose elements 21 Sporangia single not forming complexes 22

21(20) Antheridia often absent.oogonial projections conical, acute, up to II .um long P. oligandrum" Antheridia present usually monoclinous; oogonial projections conical, blunt, up to 5 ..urn long P. acanthicum"

22(20) Sporangia proliferous; antheridia absent P.anandrum* Sporangia nonproliferous, antheridia present 23

23(22) Antheridia mostly hypogynous P. echinulatum" Antheridia monoclinous and diclinous 24

24(23) Oogonial projections numerous, conical and often curved P. mamillatum* Oogonia smooth or with a varying number of blunt conical or finger-like projections up to 5 projections/ oogonium P. irregu/are*

SPECIES WITH SUB GLOBOSE SPORANGIA 25(3) Sporangia not proliferating or only hyphal swellings present 26 Sporangia proliferating 45

SPROANGIA SUBGLOBOSE, NON-PROLIFERATING, OR ONLY HYPHAL SWELLINGS PRESENT

26(4) Sporangia consisting of subglobose elements only 27 Sporangia consisting of both globose or pyriform elements and toruloid parts P. pyri/obum

27(26) Subglobose zoosporic sporangia present 28 No zoosporic sporangia, only hyphal swellings present 41

28(27) Oospores plerotic or nearly so 29 Oospores aplerotic 33

12 29(28) Antheridia typically hypogynous P. hypogynum Antheridia mono - or diclinous occasionally hypogynouns or absent 30

30(29) Antherid ia monoclinous, typically sessile or hypogynous, oogonia usually intercalary P. rostratum* Antheridia never hypogynous, oogonia terminal or intercalary 31

31(30) Oogonia 15.1± 0.6-95% c.Iurn diam, intercalary, often in chains of 2-5; antheridia often absent P.salpingophorum* Oogonia terminal and intercalary, antheridia present 32

32(31) 22 urn diam in average, thick-walled chalmydospores present. maximum temperature 300C P. tracheiphilum Sporangia 18 urn diam in average, chlamydospores absent, maximum temperature about 400C P. orthogonon 33(28) Oogonia smooth 34 Oogonial wall with finger-like projections 0-5/ oogonium P. irregulare*

34(33) Antheridia typically bell-shaped, I or rarely 2/ oogonium P. vexans* Antheridia not bell-shaped 35

35(34) Oogonia mostly intercalary often in chains 36 Oogonia mostly terminal, occasionally intercalary 37

36(35) Antheridia 1-2/ oogonium mostly hypogynous occasionally monociinous or diciinous, sporangia occasionally catenulate together through lateral growths P. pulchrum* Antheridia 1-5/ oogonium, mostly monociinous, sometimes sessile, diclinous, occasionally hypogynous or intercalary, sporangia not catenulate P. paroecandrum*

37(35) Antheridia mostly monoclinous originating immediately from below the oogonium, occasionally hypogynous. 38 Antheridia monociinous and diciinous, stalked, never hypogynous 39

38(37) No sporangia and toospores sproduced, hyphal swellings germir ate by germ tubes P. ultimum v. ultimum" Sporangia and zoospores produced at room temperature; hyphal swellings absent P. ultimum var. sporangiiferum 39(3) Sporangia>26 urn diam III average P. iwayamai* Sporangia<25 urn diam III average 40

13 40(39) Oogonia 19.7± 0.8-95% C.I)lm diam; antheridia 1-2(-3)/ oogonium, not branched. P. debaryanum

41(27) Oogoni~sproduced in singlecultures, oospores plerotic 42 Oogonia not produced in single cultures' oospores aplerotic ' 44 42(41) Antheridia absent P. conidiphorum* Antheridia present 43 43(42) Oogonia intercalary often in chains; oospores typically single; antheridia 1-2/oogonium, typically hypogynous P.parvum Oogonia oftern terminal; oospores 1-5/oogonium; antheridia I-51 oogonium, monoclinousor diclinous P. minor

44(41) Hyphal swellings up to 32 (av. 26.4± 0.5-95% C.I) JIm diam, usually germinating by 1(-2) germ tubes each P. sylvaticum" Hyphal swellings up to 44 (av 40»)lm diam, often with dark, densely granulated contents, each usually germinating by 1-5 germ tubes P. splendens

Oogenia 26.4± 1.3 - 95% C.I. urn diam, antheridia 1-2 (-5) oogonium, occasionally branched, 2-3 branches P. lucens

SPORANGIA PROLIFERATING 45(25) Oogonia 16.0 urn diam in average, often in chains; oospores plerotic; antheridia often absent, when present monoclinous or diclinous P. salpingophorum" Oogonia 17.5,um diam in average; oospores aplerotic, antheridia monoclinous, diclinous, or hypogynous 46

14 46(45) Oogonia mostly intercalary, occasionally terminal 22.8± 1.1-95%C.lllm diam; antheridia monoclinous, stalked or sessile, diclinous or hypogynous P. middletonii* Oogonia terminal 18.6± 0.6-95% C.I JIm diam, antheridia single, stalked, monoclinous; no diclinous or hypogynous antheridia present P. nagaii*

HETEROTHALLIC SPECIES AND SPECiES WITHOUT OOGONIA

47(1) Sporangia and zoospores produced 4-8 Sporangia not produced, only subglobose hyphal swellings present 51

48(47) Sporangia filamentous inflated or not, oogonia not produced in dual cultures 49 Sporangia globose non-proliferating, oogonia produced or not in dual cultures 50

49(48) Sporangia filamentous not inflated P. group 'F' Sporangia lobulated inflated P. group 'L'

50(48) Sporangia globose, nonproliferating; oogonia not produced in dual cultures P. group 'G' Sporangia globose catenulate, non proliferating, oogonia produced in dual cultures P. intermedium"

51(47) Oogonia not produced in dual cultures P. group 'HS' Oogonia produced in dual cultures 52

52(51) Hyphal swellings large 40 AIm diam in average, often with dark, densely granulated contents, germinating with 1-5 germ tubes; antheridia 1-8 / oogonium P. splendens" Hyphal swellings smaller, 24.4 JIm diameter in average, with brownish coloured contents, germinating with \-2 germ tubes; antheridia 2-4/ oogonium P. sylvaticum"

15 IV. DESCRIPTIONS OF SPECIES

Whenever possible two to three isolates of each Pythium species have been deposited in the Fungus Culture Collection of An-Najah University (F C C A U). The following scale is used to describe the degree of presence of Pythium species in soil: constantly present, found in 80-100% of soils; mostly present, found in 60-80% of soils; often present, found in 40-60% of soils; seldom present, found in 20-40% of soils; and rare, found in 1-20% of soils.

PYTHIUM ACANTHICUM Drechsler, J. Wash. Acad. Sci. 20:408 (1930) Figs 2-7

COLONY MORPHOLOGY: Colonies on CMA showing a distinct rosette pattern; no aerial mycelium. MYCELIUM: Main hyphae 2.5-5 (av.3.2).um wide. SPORANGIA: often intercalary, occasionally terminal; subglobose 15-28 (av. 20.6± 2.1-95% C. Ij um diam, often forming complexes of irregular subglobose elements attached together by filamentous portions. Zoospores produced in water culture at room temperature. OOGONIA:Mostly terminal,occasionally intercalary, globose 14.0-24.0 (av. 20.6 ± 0.6-95% C.I) .urn in diam; wall echinulate, spines conical with blunt tips, 1-6 (av. 3.5).um long. ANTHERIDIA: 1(-2)joogonium, mostly monoclinous arising at distance upt to 25)lm below oogonium base, rarely diclinous, often possessing branched vegetative prolongations; antheridial cells often inflated with few constrictions applied to the oogonium with narrow or broad contact interph ase. OOSPORES: plerotic, 17-21 (av.19.4 ± 0.5-95% C.I).um diam, wall 1.5 ± 0.12 95% C.I.um thick, coplast 9-13 (av. 10) .urn diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 100 C ,optimum25-300 C, maximum 370 C, Daily growth rate on CMA at 250 C 9mm. MATERIAL EXAMINED: ex soil, Tulkarm (FCCAU IOU); ex soil, Gaza (FCCAU 101.2) ex Malus sylvestris (L.) Mill, Nablus (FCCAU 101.6), and several other isolates.

OCCURRENCE: Infrequently isolated from diseased roots, stream water, and stream bed.

16 Figs. 2-7 Pythium acanthicum. (2,3) habit showing hyphae and oogonia. (4.5) sporangia. (6,7) oogonia and antheridia (Bars= 10 urn).

17 PYTHIUM ANANDRUM Drechsler J. Wash. A cad. Sci. 20:410 (1930) Figs 8-19

COLONY MORPHOLOGY: Colonies on CMA forming a radiate pattern with scanty aerial mycelium. SPORANGIA: Terminal, elongate (35-50)X(25-35) avo 41X30.um diam, usually papillate, proliferating. Zoosperes formed at room temperature, discharge tubes short up to Ifl um long; zoospores rarely forming and germinating within the sporangium. OOGONIA: Terminal, globose, 23-29 (av. 26.5 ± 0.8-95% C.l.) .um diam, ornamented with conical pointed spines, 3-11 (av. 2.5).urn long. ANTHERIDIA: Lacking. OOSPORES: Aplerotic 20-25 (av. 22.9 ± 0.6-95% c.!.) urn thick. Ooplast 12-17 (av. 14) .um, TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 50 C, optimum 20-250 C, maximum 300C. Daily growth rate on CMA at 250C 18mm diam. MATERIAL EXAMINED: ex :Lantana sp, Nablus (FCCAU 139.1); ex stream water, Til-Nablus (FCCAU 139.2); and ex stream bed, Nablus (FCCAU 139.3). OCCURRENCE: Infrequently isolated from diseased roots, stream water, and . stream bed.

18 Figs. 8-11. Pythium anandrumn. Sporangia, some proliferating. (Bars:lO urn).

\9 Figs. 12-15. Pythium anandrum. (12,14) habits showing hyphae, oogonia and sporangia. (13) proliferating sporangium. (15) zoospores forming and germinating inside a sporangium. (Bars-IO .urn).

20 Figs. 16-19. Pythiurn anandrurn. Oogonia (Bars=10.um).

_ 21 __ I PYTHIUM APHANIDERMATUM(Edson) Fitzp, Mycologia 15:168 Figs 20- 23

COLONY MORPHOLOGY: Colonies on CMA forming a diffuse growth pattern with cotony aerial mycelium. MYCELIUM: Main hyphae up to II urn wide. SPORANGIA:Mosdy terminal consisting of complexes of swollen torulated hyphai bodies. Zoospores formed at room temperature. OOGONIA:Tertnlnai, globose, smooth 18-29 (av. 22.7 ± 0.1-95% C.I),um diam. ANTHERIDIA:Mostiy intercalary, occasionaly monoclinous or diclinous, 1(-2)/ oogonium. OOSPORES: aplerotic) 15-25 (av. 19.2 ± 0.6-95% C.I) urn diam. wall 1-2 (av. 1.2 ± 0.3-95% c.I.)pm thick. Ooplast 5-12 (av. 9.3) urn ciam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 100C, optimum 35-400C, maximum 400 C Daily growth rate on CMAat 250 C 28mm. MATERIAL EXAMINED: ex Solanum melongona L., Ram Alla' (FCCAU 102.27); ex Cucurbita sp, Nablus (FCCAU 102.26); ex sp, Gaza (FCCAU 102.25) ex soil Jordan Valley (FCCAU 102.10), and several other isolates. OCCURRENCE: Frequently isolated from diseased roots and damped-off seedlings, and often present (in 45% of the fields) in irrigated soils; it was not found in nonirrigated fields. This species was also recorded from Cucurbitaceae and tomato in Palestine (Reichert, 1939), and thought to be 'common in soils in Israei' (Solei & Pinkas, 1984).

22 Figs. 20-23. Pythium aphanidermatum.i an habit showing hyphae and inflated filamentous sporangia. (2! -23) oogonia with intercalary antheridia (Bars: 10 urn). 23 PYTHIUM COLORATUM , Vaartaja, Mycologia 57:417 (1965). Figs 24-26

COLONY MORPHOJ..,OGY: Colonies on CMA forming an indistinct chrysanthemum growth pattern; no development of aerial mycelium. MYCELIUM: Main hyphe 3-6 (av. 4) um wide. SPORANGIA:Filamerrtous, terminal Or intercalary, slightly inflated. Zoospores formed at room temperature, vesicles up to 55 urn diam. OOGONIA: Terminal, or occasionally intercalary, globose Or pyriform, smooth sometimes with papilla, 17-23 (av. 19.7 ± 0.8-95% C-I) urn diam. ANTHERIDIA: Diclinous and monoclinous, 1- 4/ oogonium, clavate, crooknecked, antheridial stalk sometimes branching into two branches with a septum at the branching point, one antheridial cell is borne at each branch. OOSPORES: Aplerotic, 12-19 (av. 16.2 ± 0.7-95% C.I) .urn diam, wall 1-2 (av. 1.7 ± 0.2-95% C.l.).um thick. Ooplast 6-11 (av. 7.7)um diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 50C, optimum 250C, maximum 300C. Daily growth rate on CMA at 250C 13.8mm. MA TERIAL EXAMINED: ex Raphanus sativus L., Ram AlIa' (FCCAU /03.6); ex Lens culinaris Medik, Nablus (FCCAU 103·7); ex soil, Bethlehem (FCCAU 103.1), and several other isolates. OCCURRENCE: Infrequntly isolated from diseased roots and stream water, and rarely from soil (found in 15% of the soils sampled).

PYTHIUM CONIDIOPHORUM Jokl, OSlo bot. Z. 67:33-36 (1918) Figs 27- 29

COLONY MORPHOLOGY: Colonies on CMA forming a diffuse pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-6.um wide, no catenulate appressoria ever observed. SPORANGIA and zoospores not formed. HYPHAL SWELLINGS: Terminal and intercalary, globose, dark, granulated, usually germinating by several germ tubes, 16-30 (av, 21.8±0.8-95% Cd.uim diam. OOGONIA: Mostly terminal, occasionally intercalary, smooth, 7-16 (av. 13.1 ± 0.5-95% C.l.),um diam. ANTHERIDIA: Absent. OOSPORES: Plerotic, wall 1-2.5 (av. 1.8± 0.2-95% C.l.),um thick. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum 0-50 C, optimum 200 C, maximum 30-35 C. Daily growth rate on CMA at 250 C 12mm. MATERIAL EXAMINAD: ex soil, Bethlehem (FCCAU 115.1);and ex stream bed, Nablus (FCCAU 115.2; FCCAU 115.3). OCCURRENCE: Rarely isolated from soil (found in 2% of the fields sampled and stream bed. 24 Figs. 24-29. (24-26) Pvthium c%rotum;(24) sporangia! vesicle; (25,26) oogonia with antheridia. (27-29)P. conidiophorum;(27) habit showing hyphae and hyphal swellings; (28,29) oogonia. (Bars: 10 urn).

25 PYTHIUM DEBARYANUM auct. non Hesse, Waterhouse, Mycol. Pap. 109, 15pp. (1967) (as de Baryanum); Hesse, Inaug. Diss. Halle: 1-76(1874). Figs. 30-33

COLONY MORPHOLOGY: Colonies on CMA showing a radiate growth; some aerial mycelium developed especially around petri dish margin. MYCELIUM: Main hyphae 2.5-6 (av. 3.4)llm wide. SPORANGIA: Terminal or intercalary, globose to subglobose, 15-35 (av. 24.1 ± 1,7-95% c.!.) urn diam. Zoospores produced at 5-1S-C. OOGONIA: Mostly terminal, globose, 16-25 (av. 19.7 ± 0.8-95% c.i.) urn diam. ANTHERIDIA: 1-2(-3)foogonium, mostly monoclinous, originating at some distance from oogonium base, never hypogynous or sessile, occasiounally diclinous, mostly club-shaped. OOSPORES: Aplerotic, 15-20 (av. 16.4 ± 0.4-95% c.L).um diam, wall 1-2 (av. 1.2 ± 0.195% c.i.) urn thick, ooplast 7-11 (av. 8.9 ± 0.3 95% C.I.) .urn diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5° C, optimum 23-30oC, maximum 350C. Daily growth rate on CMA at 250C 23.8 mm. MATERIAL EXAMINED: ex Psidium guayava L., Nablus (FCCAU 104.3);ex Prunus amygdalus (L.) Batch, Nassareyeh (FCCAU 104.4); and ex soil, Hebron (FCCAU 104.1). OCCURRENCE: Infrequently isolated from roots, and rarely from soil (found in 6% of the soils sampled). This species was also isolated from diseased roots of Cucumis sativus L. and Lycopersicon esculentum Mill in Jordan, (Mamluk, Skaria & Abu-Blan, unpublished, in Mamluk et al., 1984; Vestal, 1954).

PYTHIUM DELIENSE Meurs, Phytopath.Z. 7:179 (1934).

OCCURRENCE: Rarely isolated from irrigated fields (in 9% of the soils sampled); it was absent in nonirrigated fields.

26 Figs. 30-35. (30-33) Pythium debaryanum; oogonia and antheridia. (34.35) Pythium intermedium; catenulate sporangia. (Bars: 10 urn).

27 PYTHIUM DIMORPHUM Hendrix & Campbell, Mycologia 63:979 (1971).

OCCURENCE: This species was isolated only once from a soil in Tulkarem.

PYTHIUM DISSIMILE Vaartaja, Mycologia 57:421 (1965). Figs 36-41

COLONY MORPHOLOGY: Colonies on CMA forming a radiate growth pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 2.5-6 (av. 3).Almwide. SPORANGIA: Terminal or intercalary,consisting of complexes of toruloid outgrowths of hyphae. Zoospores readilly produced at 1O-20oC. OOGONIA:Terminal, occasionaly intercalary, globose, smooth 10-15 (av. 12.4 ± 0.4-95% c.1.).Alm diam. ANTHERIDlA:Mostly lacking, rarely hypogynous, monoclinous or diclinous. OOSPORES: Plerotic, wall 1-1.5 (av. 1.0 ± 0.4-95% c.I.)..um thick. Ooplast 5-8 (av. 6.3)..um diam. TEMPERATURE-GROWTH e RELA TIONSHIPS: Minimum ro-c, optimum 20-25°C, maximum 30C. Daily o growth rate on CMA at 25C 6.4mm. MATERIAL EXAMINED: ex Viciafabae L., Jenin (FCCAU 106.6); ex soil, Gaza (FCCAU 106.1), Nablus (FCCAU 106.2), and several other isolates. . OCCURRENCE: infrequently isolated from diseased roots, and also rarely from irrigated soils (found in 14% of these soils); it was absent in nonirrigated soils. Only a few records are known for this species. It has been recorded from soil and Pinus radiata in Australia (Vaartaja, 1965), from soil in the Netherlands (Plaats - Niterink, 1975), from agricultural soils in Germany (in Plaats- Niterink, 1981), from cultivated soils in England (Ali, 1982) and the West Bank of Jordan (AIi, 1985)

28 Figs. 36-41. Pythium dissimile. (36,37) inflated toruloid sporangia. (38,39) oogonia with hypogynous antheridia. (40,41) oogonia. (Bars= 10urn). 29 PYTHIUM DISSOTOCUM Drechsler 1. Wash. Acac. Sci. 20:402 (930).

COLONY MORPHOLOGY: Colonies on CMA forming a distinct chrysanthemum growth pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 4-7 (av. 4.3),um wide. SPORANGIA: Filamentous, slightly inflated. Zoospores formed at IO-20°C. OOGONIA: Mostly terminal, sometimes intercalary, subglobose, smooth, 15-22 (av. 18.4 ± 0.7-95% ~.I.),um diam, occasionaly with papilla. ANTHERIDIA: 1-3/ oogonium. Mostly monoclinous commonly sessile arising from the oogonial stalk immediately below the oogonium, sometimes diclinous, antheridial stalks unbranched. OOSPORES:Aplerotic, 12.5-18 (av. 15.1 ± 0.5-95% c.I.)..um diam, wall 1-2.5 (av. 1.4 ± 0.13-95% C.lJ .um thick. Ooplasts 6-12 (av. 8) .nm diam. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum 5C, optimum 20- 250 C, maximum 350 C. Daily growth rate on CMA at 250 C 11.4mm. MATERIAL EXAMINED:ex Lens culinaris Medik, Tubas (FCCAU 136.4); and ex soil, Nablus (FCCAU 136.1 & FCCAU 136.2). OCCURRENCE:Infrequently isolated from diseased roots, and rarely from soil (found in only one soil). This species was also recorded from soil in the Lebanon (Ahrens, 1971).

3() Figs. 42-47. Pythium dissotocum. (42,43) habits showing hyphae, filamentous sporangia, and oogonia. (44-47) oogonia with antheridia (Bars= IO.llm).

31 PYTHIUM ECHINULATUM Matthews, Studies on the Genus Pythium, (Univ. of Carolina Press) p. 101 (1931). Figs 48-54

COLONY MORPHOLOGY:Colonies on CMA forming a rosette growth pattern; no development of aerial mycelium. MYCELIUM:Main hyphae 3-7 (av. 4.4),um wide. SPORANGIA: Subglobose to elongate, terminal or intercalary, sometimes 3 to 5 in a chain, (13-40)x( l3-33) avo 27x24..um diam. Zoospores produced at 5-20° C. OOGONIA: Terminal or intercalary, subglobose, 17-23 (av 20.9± 0.5-95% c.i.) .urn diam, provided with conical pointed spines 8-14 (av.11.0) AIm long. ANTHERIDIA: Typically hypogynous, 1-2/ oogonium. rarely monoclinous sessile. OOSPORES:Aplerotic (oospore vol. I oogonium vol.- 0.69),single, sometimes 2/00gonium, 15-21 (av. 18.5± 0.4-95% C. I.),.um diam, wall 1-1.5 (av. 1.2± 0.1-95 % C.I.)llm thick. Ooplast 7-11 (av. 9.6)..um diam. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum 5°C, optimum 20- 300 C, maximum 350 C. Daily growth rate on CMA at 250C 8.4mm. MATERIAL EXAMINED: ex soil, Nablus (FCCAU 127.1), Jenin(FCCAU 127.2), and Ram Alia" (FCCAU 127.3). OCCURRENCE:Seldom present in irrigated fields (found in 23% of these soils); it was absent in nonirrigated fields.

32 Figs. 48-54. Pythium echinulatum. (48,50,52-54) oogonia, (49) vesicle with zoospores. (50) sporangium with a discharge tube. (Bars- \0 urn).

33 PYTHIUM GRAMINICOLA Subramaniam, Bull. Agric. Res. Pusa 177:5(1928) (as 'graminicolum'i. Figs 55-59

COLONY MORPHOLOGY:Colonies on CMA forming a radiate pattern with scanty aerial mycelium. MYCELIUM:Main hyphae 2.5-4(av. 3.4»)Jm wide. Appressoria subglobose or irregular. SPORANGIA: Terminal or intercalary, consisting of inflated lobulated irregular complexes of hyphal bodies. Zoospores formed at 5-200C. OOGONIA:Terminal or intercalary, smooth, globose, 20-33 (av. 26.1± 1.3-95% c.I.»).lm diam. ANTHERIDIA: 1-3/ oogonium, mostly monoclinous, occasiounally diclinous; antheridial stalk sometimes branching into two branches each bearing an antheridial cell, occasionally entwining the oogonial stalk. OOSPORES:Plerotic, occasionally 2-3 oospores/ oogonium; wall 1-3(av. 2.5± 0.1-95% C.I) .um thick. Ooplast 10-18 (av. 13.4)..um diam. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum So C, optimum 2SoC, maximum 300e. Daily growth rate on CMA at 2SoC7mm. MATERIAL EXAMINED: ex soil, Nassareyeh (FCCAU 141.1; FCCAU 141.2; FCCAU 141.3). OCCURRENCE: Isolated only once from an irrigated field under vegetables after wheat.

PYTHIUM HYPOGYNUM Middleton, Mem. Torrey bot. Club 20:69(1943).

OCCURRENCE: Rarely isolated from irrigated fields (found in 14% of the soils): it was absent in nonirrigated fields.

34 Figs. 55-59. Pvthium graminicola. (55) habit showing hyphae and sporangia. (56-59) oogonia with autherid ia. (Bals: 10 urn).

35 PYTHIUM INTERMEDIUM de Bary Bot. Ztg: 554 (1881). Figs 34-35

COLONY MORPHOLOGY:Colonies on CMA forming a radiate pattern.no development of aerial mycehum. MYCELIUM: Main hyphae 3.5-7(av. 4.8»)lm wide. SPORANGIA: Subglobose or spherical, 16-24(av. 19.4).um diam, mostly terminal, occasionally intercalary, 2-8 in a. chain. Zoospores formed in water culture in the presence of grass blade at 5-15C SEXUAL STRUCTURES: Attempts to produce oogonia in dual cultures were not successful; identification was based on vegetative structures. TEMPERATURE _ GROWTH RELATIONSHIPS: Minimum 5°C, optimum 250C, maximum 300e. Daily growth rate on CMA at 25°C 21mm.

MATERIAL EXAMINED: ex Rosa sp, An-Najah University campus (FCCAU 107.2);ex soil, Nablus (FCCAUI07.1), and Ram AlIa (FCCAUl07.3) and several other isolates. OCCURRENCE:Infrequently isolated from diseased roots, and rarely from soil (found in 12% of the soils sampled). This species was also recorded from soil in the Lebanon(Ahrens, 1971) and from fresh water in Egypt(El-Hissy, 1974).

PYTHIUM IRREGULARE Buisman,Meded. phytopath. Lab. Willie Commelin Scholten 11:1-51(1927).

COLONY MORPHOLOGY:Colonies on CMA forming a diffuse pattern, with a moderate amount of aerial mycelium. MYCELIUM:Main hyphae 3-7(av. 3.3) urn wide.SPORANGIA:Globose 13-35(av.25.3)jJm diam, terminal and intercalary. Zoospores produced at 1O-15oe. OOGONIA:Globose to irregular, intercalary and terminal, 15-23 (av. 18.5 ± 0.6-95% C.I.) urn diarn, smooth or with a few blunt conical finger-like projections, up to 5/ oogonium. ANTHERIDIA: 1-2(-3)/ oogonium, mostly monoclinous, usually stalked arising at some distance from oogonium base, occasionally sessile or hypogynous; antheridial stalks sometimes branched. OOSPORES:Aplerotic; IO-18(av. 15.0± -95% C.l.j nm diam, wall 0.5-1.5 (av. 0.9 ± 0.1-95% C.I)..um thick. Ooplast 6-10 (av. 7.7).um diam. TEMPERATURE - GROWTH RELATIONSHIPS: Minimum lOoC, optimum 30oC, maximum 3SoC. Daily growth rate on CMA at 250C l lmm.

36 MATERIAL EXAMINED: ex Vitia fabae, Jenin (FCCAU 108-3), Viola tricolor, Nablus (FCCAU 108.4), Euphorbia pulcherrima(R. Grah.) Willd., Jericho(FCCAU 1O~.5):ex soil, Hebron(FCCAU 108.1), and several other isolates.

OCCURRE;\lCE:Frequently isolated from diseased roots and damped-off seedlings and also often present in soil(found in 45% of the soils sampled). This species was also recorded from soil in the Lebanon (Ahrens, 1977).

PYTHIUM IW A YAMI S. ito, Trans. Sapporo nta. Hist. Soc. 14: 13(1935). Figs. 60-64; 63-64

COLONY MORPHOLOGY: Colonies on CMA forming diffuse pattern with no aerial mycelium. MYCELIUM: Hyphae 3-7(av.4.8»).lm wide. SPORANGIA: Mostly terminal, occasionally intercalary, globose, some of which thick-walled germinating by germ tubes, 20-43(av.28.8»).lm diam. Zoospores formed at 10-200 C. OOGONIA:Mostly terminal, occasionally intercalary, globose, smooth, 15- 28(av. 23.8± 0.6-95% C.I»).lm diam. ANTHERIDIA:I-3/00gonium, monoc1inous or dic1inous, antheridial stalks occasionally branching into 2-3 branches. OOSPORES:Aplerotic, 14-22(av. 19.5± 0.5-95% c.I.) jim diam. Ooplast 9- 13(av.ll»).lm diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 50 C,optimum 250C, maximum 30oC. Daily growth rate on CMA at 250C 14mm.

MATERIAL EXAMINED: ex Lycopersicon esculentum Mill, Tulkarem (FeCAU 109.6), Allium cepa L., Jenin (FCCAUI09.7), and Triticum aestivum L., Nablus (FCCAU 109.8); and ex soil, Bethlehem (FCCAUl09.1). OCCURRENCE:Frequently isolated from diseased roots and damped-off seedlings, but seldom present in soil (found in 24% of the soils sampled).'

PYTHIUM LUCENS Ali-Shtayeh, Bot. J. Lin. Soc. 91: 297-317 (1985).

OCCURRENCE: This species was originally isolated from soil in England. It seems to be rare in this area: it was isolated only once from an irrigated feild in the Jordan Valley •

37 Figs. 60-64. (60-62) Pythium irregulare, (60) intercalary oogonia and sporangia, (61,62) oogonia with antheridia; 63-64) P. iwayamai, (63) oogonium with antheridiurn, (64) intercalary conidium. (bars, 10 .urn).

38 PYTHIUM LrTARIL:\l Ali - Shtaveh, Boi.:'. Lin. Soc. 91:297-317(1985).

OCCURRENCE:This species was originally isolated from soil in England. In this area it was infrequently isolated from diseased roots, and seldom present in soil(found in 24% of soils sampled).

PYTHIUM MAMILLATUM Meurs, Wortelrot veroorzaakt door schimmels uit de geslachten Pythium en Aphanomyces, Diss. Univ. Utrecht, p 44(1928) Figs. 65-72

COLONY MORPHOLOGY:Colonies on CMA forming indistinct rosette pattern with development of some aerial mycelium. MYCELlUM:Main hyphae 3-7(av.4.2) .um wide. SPORANGIA:Terminal and intercalary, globose or ellipsoidal 13-30 x 11-27(av. 20.3 x 18.6).um diam; zoospores formed at 1O-20C,• emmision tubes short, up to 5 ..urn long; rarely proliferating inernally. OOGONIA:Terminal or intercalary, globose, 12-22(av.17.9± -95% C.I) urn diam, provided with many projections, 4-9(av. 5.5).um long, projections obtuse, conical and often curved; occasionally smooth oogonia present. ANTHERIDIA: 1-2/ oogonium, mostly monoclinous and originating at a distance from oogonium base, rarely sessile arrising just below oogonium base, occasionally diclinous; antheridial stalks rarely branched, antheridial cells mostly clavate. OOSPORES: Plerotic, 11-20(av. 16.7± 0.7-95% c.1.)..um diam. Ooplast 6-11 (av. 8.5)..um diam. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum 50C, optimum 250C, maximum 37oC. Daily growth rate on CMA at 250C 21.88. MATERIAL EXAMINED: ex soil, Ram Alia' (FCCAUI28.1; FCCAU128.2; FCCAU 128.3). OCCURRENCE: Rarely isolated from soil, it was found in only one of the soils sampled.

39 Figs. 65-72. Pythium mamillatum. (65) habit showing hyphae and sporangia. (66;70-72) oogonia with antheridia. (67) oogonium and empty sporangium. (68,69) sporangia. (BarsetO .um),

40 PYTHIUM MIDDLETON II Sparrow, Aquatic Phycomycetes(Univ. of Mitch. Press), p.1038(1960).

COLONY MORPHOLOGY:Colonies on CMA forming chrysanthemum pattern with no aerial mycelium. MYCELIUM:Main hyphae 3-8(av. 4).um wide. SPORANGIA: Globose, ovoid, proliferating internally, (25-50)x(21-38) (av. 38 x 35) urn diam. emmision tubes short, zoospores formed at 10-20 C. OOGONIA: Mostly intercalary, occasionally terminal, subglobose, 15-30(av. 22.8± 1.1-95% C.I.) ..urn diam. ANTHERIDIA:Monoclinous, stalked or commonly sessile, diclinous and hypogynous; mostly 1/ oogonium. OOSPORES: Aplerotic, 14-25(av.19.0± 0.9 -95% c.1.)..um diam, wall 1-2 (av. I.4± 0.2 -95% c.1.)..um thick; ooplast 6-15(av,IO.3)..um diam. TEMPERATURE - GROWTH RELATIONSHIPS: Minimum IOoC, optimum 250C, maximum 30°C. Daily growth rate on CMA at 25°C 1O.lmm. MATERIAL EXAMINED: ex Diospyros kaki L.,Tulkarem(FCCA U II 1.8) and lens culinaris Medik, Tubas(FCCA U 111.9);ex soil, Nablus(FCCA U 111.1);ex stream water, Nablus(FCCAU 111.10), and several other isolates. OCCURRENCE: Infrequently isolated from diseased roots, seldom present in soil (found in 24% of the soils studied) and also infrequently isolated from stream water. This species was also recorded from damped-off soyabeans in Egypt (EI-Helaly et al., 1972) and from diseased roots of avocado in Israel{Pinkas et al. 1981)

PYTHIUM MINOR Ali-Shtayeh, Bot. J. Lin. Soc. 91:297-317{l985).

OCCURRENCE:Seldom present in soil (found in 27% of the soils sampled), and also found in stream water.

41 Figs. 73-78. Pythium middletonii.(3)habil showing hyphae and sporangia. (74,75) sporangia, one proliferating internally. (76-78) oogonia with antheridia. (Bars;\0 .urn). 42 PYTHIUM MONOSPERMUM Pringsh., Jb. wiss. Bot. 2:288(1858). Figs. 79- 84.

COLONY MORPHOLOGY:Colonies on CMA showing a chrysanthemum pattern with no aerial mycelium. MYCELIUM: Main hyphae 5-8(av. 5.2) urn wide. SPORANGIA:Filamentous, noninflated. Zoospores produced at 5_20°C. OOGONIA:Terminal and intercalary, smooth, l5-20(av. l7.2± 0.6-95% C.!.)).lm diam. ANTHERIDlA:I-2(-5)joogonium, monoclinous and diclinous, OOSPORES: Plerotic, wall 1-2(av. I.O± 0.1-95% C.I.) urn thick; ooplast 5-8 (av. 7.3),um diam. TEMPERATURE-GROWTH RELATIONSHIPS:Minimum 50C, optimum 250C, maximum 300e. Daily growth rate on CMA at 250C 11.6mm·.;" MATERIAL EXAMINED: ex soil, Jenin(FCCAU 113.1; FCCAU 113.3).

OCCURRENCE: Rarely isolated from soil; it was found in only one of the fields sampled.

PYTHIUM MYRIOTYLUM Drechsler, J. Wash. Acad. Sci. 20:404(1930).

OCCURRENCE:lnfrequently isolated from diseased roots and rarely from soil (found in one field). Other records from the region come from in Israel(Frank, 1968) and Libya(Pucci, 1969).

PYTHIUM NAGAII S. Ito & Tokunga, J. Fac. Agric. Hokkaido Univ. 32:209( 1933). Figs. 85-90,85

COLONY MORPHOLOGY:Colonies on CMA showing a diffuse pattern;scanty aerial mycelium developed. MYCELIUM: Main hyphae 3-5(av.3.5) urn wide. SPORANGIA: Terminal, ovoid, occasionally globose, (I8-35)x(l5-25) (av. 25x21) .um diarn, occasionally proliferating; zoospores produced at 1O-150C. OOGONIA: Terminal, occasiounally intercalary, smooth, 16-23 (av. 18.6± 0.6 43 Figs. 79-84. Pvthium monospermum. Oogonia with antheridia. (Bars; 10 urn). 44 Figs. 85-90. (85) Pythium nagaii, oogonium with antheridium; (86-88) p. paroecandrum,oogonia with antheridia; (89-90) P. pulchrum. (89) oogonium with hypogynous antheridium, (90) catenulate sporangia. (Bars: 10urn).

45 -95% CI.) .urn diam. ANTHERIDIA: Mostly monoclinous, occasionally diciinous,I(-2)/oogonium, clubshaped. OOSPORES:Aplerotic, 15-18(av. 15.5± 0.4- 95% Cl.) ..urn diam; ooplast 7-10 (av. 8) .urn diam. TEMPERATURE- GROWTH RELATIONSHIPS:Minimum 5°C, optimum 25°C, maximum 300C. Daily growth rate on CMA at 25 COI5.6mm. MATERIAL EXAMINED: ex stream bed, Nablus (FCCAU 144.2). OCCURRENCE:Isolated only once from stream bed near Nablus.

PYTHIUM OLIGANDRUMDrechsler, J. Wash Acad. Sci. 20:409(1930) Figs. 91-94

COLONY MORPHOLOGY: Colonies on CMA show no special pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-6 (av. 4»).Im wide. SPORANGIA: Terminal or intercalary, consisting of complexes of subglobose elements connected together with filamentous parts, 18-35 (av,2.5) ...urndiam. Zoospores formed at 1O-20oC OOGONIA: Terminal or intercalary, globose, 15-26 (av.20.8± 0.8-95% C.I.)...um diam, provided with conical pointed projections, 5-11 (av. lO)pm long. ANTHERIDIA: Mostly lacking, diclinous or occasionally monoclinous, antheridial cells often applied lengthwise closely to the oogonium, sometimes lobulated or constricted. OOSPORES: Aplerotic (oospore volume/oogonium volume=0.70), 13-20 (av. 18.5± 0.6-95% C.l.Lum diam, wall 1-2 (av. 1.7± -95% C.I.)...um thick, ooplast 6-13 (av.9.8)...um diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 1

MATERIAL EXAMINED: ex Phaseolus vulgaris L., Nassareyeh (FCCAUl14.50), Cucurbita pepo L. var melopero, Nablus (FCCAU 114.47); ex soil, Ram AlIa' (FCCAU 114.30), and several other isolates. OCCURRENCE: Frequently isolated from diseased roots and, damped-off seedlings, and also constantly present in soil (found in 85% of the soils sampled). This species was also recorded from soil in Negev (Frank, 1968).

46 Figs. 91-94. Pythium oligandrum.(91) habit showing hyphae, sporongia and oogonia. (92) sporongia and oogonia (9.\. 94) oogonia. (Bars, 10 AIm).

47 PYTHIUM ORTHOGONON Ahrens, Z. Pflkrhk.Pflschutz . 78:177(1971).

OCCURRENCE: Infrequently isolated from diseased roots and rarely from soil (found in 6% of the soils sampled). In addition to its original isolation. from the Lebanon (Ahrens, 1971) this species was also recorded from cultivated soils in England (Ali, 1982) and the West Bank of Jordan (Ali,1985).

PYTHIUM PACHYCAULE Ali-Shtayeh, Bot. J. Lin. Soc. 91:297-317(1985).

OCCURRENCE: Infrequently isolated from diseased roots and rarely from soil (found in 6% of the soils sampled).

PYTHIUM PAPILLATUM Matthews, J. Elisha Mitchell scient. Soc .. 43:231 (1928). Figs. 95-100

COLONY MORPHOLOGY: Colonies on CMA showing a vague chrysanthemum pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3.5-6 (av. 4.1) .um wide. SPORANGIA: Filamentous, slightly thicker than hyphae, branched or unbranched, terminal or lateral. Zoospores produced at 1O-26c. OOGONIA: Terminal, occasionally, globose, smooth, 13- 18 (av. 15.3± 0.4-95% C.l).llm diam, or provided with 1-5 papillae, papilla up to 15 .urn long. ANTHERIDIA: Mostly lacking, occasionally 1/ oogonium monoclinous, mostly sessile originating just from below oogonium base. OOSPORES: Plerotic, wall 0.5-1 (av. 0.8± 0.195% C.I).llm thick; ooplast 5-8 (av. 7.2) .urn diam. TEMPERATURE-GROWTH RELATIONSHIPS: o • 0 minimum 10 C, optimum 25 C, maximum 30 C. Daily growth rate on CMA at 25• C 1.6mm.

MATERIAL EXAMINED: ex stream water, Nablus (FCCAU 146.2). OCCU REN CE: This species seems to be very rare. Only a few records have been published since it was first isolated from soil in the USA. These other records came from Hordeum vulgare in the USA (Middleton, 1943), from water in the USSR (Meshcheryakova & Logvinenko, 1970), and from soil in England (Ho , 1975; Ali 1982). In this work, the species was isolated from a freshwater stream near Nablus.

48 Figs. 95-100. Pythium papillaturn. (95) filamentous sporangia. (96-99) oogonia with papillae. (100) oogonium with sessile rnonoclinous ant herid iurn. (Bars: 10 .um).

49 PYTHIUM PAROECANDRUM Drechsler, J. Wash. Acad. Sci. 20:406 (1930). Figs. 86-88.

COLONY MORPHOLOGY: Colonies on CMA showing a radiate pattern. MYCELIUM: Main hyphae 3-8 (av. 4.6).,um wide. SPORANGIA: Subglobose or ellipsoidal, 17-33 (av. 23.0± 1.4-95% CI)).lm diam. terminal or intercalary, sometimes 2-3 in a chain, zoospores produced at 10-20 C. OOGONIA: globose, mostly intercalary, occasionally in chains, occasionally terminal, smooth, 16-28 ..urn (av. 22.8± 1.0-95% CI.) .um diam. ANTHERIDIA: 1-2(-5)foogonium, monoclinous, sometimes sessile, occasionally diclinous, sometimes intercalary or hypogynous. OOSPORES: Aplerotic, 15-23 (av. 18.1± 1.3-95% CI)..um diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5' C, optimum 25° C, maximum 30°C Daily growth rate on CMA at 25°C 14.8mm. MATERIAL EXAMINED: ex Vilis vinifera L., Hebron (FCCAU 117.3), Solanum melongona L., Nablus (FCCAU 117.4); ex soil, Gaza (FCCAU 117.3), and several other isolates. OCCURENCE: Frequently isolated from diseased roots and rotted collars, and seldom present in soil (found in 30% of the soils sampled). This species was also recorded from soil in the Lebanon (Ahrens, 1971).

PYTHIUM PARVUM Ali-Shtayeh, Bal. J. Lin. 91:297-317(1985).

OCCURRENCE: Infrequently isolated from diseased roots, and also seldom present in soil (found in 24% of the soils sampled).

PYTHIUM PERIPLOCUM Drechsler, J. Wash. Acad. Sci. 20:405 (1930).

OCCURRENCE: Infrequently isolated from diseased roots and rarely from soil (found in 18% of the soils sampled).

50 I PYTHIUM PULCHRUM Minden, Mykol. UntersBer. 1:277(1916). Figs. 89- 90.

COLONY MORPHOLOGY: Colonies on CMA showing an indistinct chrysanthemum pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-5 (av. 4.2) urn wide. SPORANGIA: Globose, ellipsoidal, occasionally catenulate up to 3 in a chain, 20-41 (av. 30).um diam, zoospores produced at 1O-2dC. OOGONIA: Mostly intercalary, occasionally terminal up to 5 in a series, smooth, 18-37 (av. 23.4± 1.2-95% c.I.) urn diam. ANTHERIDIA: 1-2(-3)/oogonium, mostly hypogynous. occasionally monoclinous or diclinous. OOSPORES: Aplerotic, 16-29 (av. 19.4± 0.7-95% c.I.).um diam, ooplast 9-13 (av. 1O.5)umdiam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 50C, optimum 250C, maximum 30oC. Daily growth rate on CMA at 250C 17mm. MATERIAL EXAMINED: ex Malva sp, Nablus (FCCAU 129.3), Monistera deliciosa, Qalqilyeh (FCCAU 129.4), ex soil, Gaza (FCCAU 129.1), and several other isolates. OCCURRENCE: Infrequently isolated from diseased roots, and seldom present in soil (found in 30% of the soils sampled). This species was also recorded from Iraq (Al-Doory et al. , 1959).

PYTHIUM PYRILOBUM Vaartaja, Mycologia 57:425 (1965).

OCCURRENCE: Infrequently isolated from diseased roots, and rarely form soil (found in 3% of the soils sampled).

51 PYTHIUM ROSTRA TUM Butler, Mem. Dep. Agric. bot. Ser. 1:84 )1907) Figs. 101-103

COLONY MORPHOLOGY: Colonies on CMA showing a chrysanthemum pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-6 (av. 3.6) .um wide. SPORANGIA: Terminal or intercalary, globose and subglobose, 15-35 (av. 23.1) .nm diam, zoospores produced at 10_20° C. OOGONIA: Mostly intercalary, occasionally terminal, subglobose, smooth, 14- 25 (av. 18.7± 0.9-95% c.!.)..um diam, often in chains. ANTHERIDIA: 1-2 per oogonium, monocIinous, often sessile originating immediately below oogonium base, or hypogynous. OOSPORES: Plerotic (oospore volume/ oogonium volum- 0.75),13-23 (av. 17.0± 0-7-95% c.l.)..um diam, wall 1-2 (av. 1.3± 0.1-95% C.I.) urn thick, ooplast 6-11 (av. 8.8) ..urn diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5' C, optimum 15-20· C, maximum 30C. Daily growth rate on CMA at 25°C 5.6mm.

MATERIAL EXAMINED: ex Zea mays, Nassareyeh (FCCAU 119.25), Citrus sinensis (L) Osbeck, Nablus (FCCAU 119.26); ex soil, Jenin (FCCAU 119.10), and many other isolates.

OCCURRENCE: Frequently isolated from diseased roots, and also constantly present in soil (found in 85% of the soils sampled). This species was also isolated from soil in the Lebanon (Ahrens, 1971) and Iraq (AI-Doory et al. 1959).

PYTHIUM SALPINGOPHORUM Drechsler, J. Wash. A cad. Sci. 20:507 (1930). Figs 109-114.

COLONY MORPHOLOGY: Colonies on CMA showing no special pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-6 (av. 3.6) J.Im wide, occasionally developing elongated or ovate, often catenulate appressoria present. SPORANGIA: Mostly terminal, occasionally intercalary, sometimes catenulate, occasionally proliferating, subglobose to globose, 17-28 (av. 22.5) J.Im diam, zoospores produced at 10-26 C, emmision tube usually formed near a septum. OOGONIA: Mostly intercallary, frequently in chains of

52 Figs. 101-108. (101-103) Pythium rostratum, (101,102) oogonia with hypogynous antheridia, (103) empty sporangium with discharge tube; (104-106) p. spinosum, oogonia with antheridia; (107-108) P. splendens. (107) hypha I swelling, and (108) oogonium with antheridia. (Barssl Ourn).

53 2-5, globose, smooth, 10-19 (av. 15.1± 0.6-95% C.I.) ..urn diameter. ANTHERIDIA: Mostly absent, occasionally monocIinous and originating just below oogonium base or diclinous, 1-2/ oogonium. OOSPORES: Plerotic, wall 1-2 (av. 1.5± 0.1-95% Cil.) ..urn thick. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5" C, optinum 25° C, maximum 30" C. Daily growth rate on CMA at 25"C 16mm. MATERIAL EXAMINED: ex soil, Nablus (FCCAU 120.1), Ram Alia (FCCAU 120.2), and Bethlahem (FCCAU 120.3). OCCURRENCE: Only a few records of this species are known. It has been isolated from soil in Germany (Schultz, 1950), Canada (Vaiirtaja, 1968), England (Ali, 1982) and the West Bank of Jordan (Ali, 1985) and from diseased plants in Germany (Schultz, 1950) and the USA (Middleton, 1943; Horsefall & Kertesz, 1933). In this work the species was infrequently isolated from diseased roots, seldom isolated from soil (found in 21% of the soils sampled), and was also infrequent in stream water.

PYTHIUM SPINOSUM Sawda apud Sawda & Chen, Trans. nat. Hist. Soc. Formosa 16:199 (1926). Figs 104-106.

COLONY MORPHOLOGY: Colonies on CMA showing a diffuse pattern with some aerial mycelium. MYCELIUM: Main hyphae 2.5-6(av. 4.4),um wide. SPORANGIA and zoospores not produced. HYPHAL SWELLINGS: Inercalary and terminal, globose and subglobose 13-35(av. 19.3).um diam; usually germinating by 1-3 germ tubes. OOGONIA: Terminal or occasionally intercalary, globose, 14-20(av. l7.1± 0.5- 95% c.l.j urn diam, echinulate, spines blunt digitate, 2-17(av. 10.0).um long. ANTHERIDIA: 1(-3)1 oogonium, mostly monocJinous, occasionally dicJinous. OOSPORES: Plerotic (oospore vol I oogonium v::Q.7S),14-18(av. IS.S± 0.S-9S% c.I.).um diam, wall O.S-I (av. 0.9± 0.1 -95% C.I.) .urn thick, ooplast 6-9 (av. 8.1).um diam. TEMPERATURE- GROWTH RELATIONSHIPS: Minimum S·C, optimum 2S'C, maximum 3SoC. Daily growth rate on CMA at 2SC 20.5mm.

MATERIAL EXAMINED: ex soil, Nablus(FCCAU 147.1),' and Gaza (FCCAU 147.2;FCCAU 147.3). OCCURRENCE: Rarely isolated from irrigated fields (found in 14% of the soils sampled).

54 Figs. 109-114. Pythium salpingophorum. (109,111) oogonia. (110, 112, 114) sporangia, some proliferating. (113) apprressoria. (Bars; 10 11m).

55 PYTHIUM SPLENDENS Braun, J. agric. Res. 30: 1043-1062(192S) Figs. 101- 108; 107-108.

COLONY MORPHOLOGY: Colonies on CMA showing radiate pattern with some aerial mycelium. MYCELIUM: Main hyphae 3-6(av. 4.S»)lm wide. SPORANGIA and zoospores not formed. HYPHAL SWELLINGS: Mostly terminal, rarely intercalary, globose, 3S-46 (av. 40) .um diam, often with dark densely granulated contents, germinating each by 1-5 germ tubes. SoEXUAL REPRODUCTION: Oogonia and antheridia scarcely produced in single cultures. This species was distinguished from other species by its large mostly terminal hyphal swellings. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5°C, optimum 2S-30' C, maximum 35°C. Daily growth rate on CMA at 2S~C 28mm.

MATERIAL EXAMINED: ex. Citrus sinensis (L.) Osbeck, Nablus (FCCAU 121.1); ex Cucurbita pepo L. var me/opera, Ram Alia (FCCAU121.10);ex Ficus elastica L., Tulkarem(FCCAU 121.IS);ex soil, Jordan Valley(FCCAU 121.3), and many other isolates OCCURRENCE: Frequently isolated from diseased roots, seldom present in soil(found in 21% of the soils sampled), and also infrequently isolated from stream water.

PYTHIUM SYLVATICUM Campbell & Hendrix, Mycologia 59:274(1967). Fig. liS

COLONY MORPHOLOGY: Colonies on CMA showing a diffuse pattern with some aerial mycelim. MYCELIUM: Main hyphae 3.5-IO(av. 5.5»).lm wide. SPORANGIA and zoospores not formed. Hyphal swellings: Intercalary or terminal, globose, up 'to 32(av. 26.4± 0.5-95% c.1.) urn diam. OOGONIA: Scarcely produced in single culture, formed abundantly in dual cultures of compatible isolates, contact line formed between the compatible isolates sharp to the side of antheridial isolate and diffuse towards the other isolate. Terminal or intercalary, subglobose or ovate, 21-28(av. 23.0± 0.7-95% c.!.»).lm diam. ANTHERIDIA: Diclinous, 1-4/oogonium;antheridial stalks mostly branched, often entwining oogonial stalk. OOSPORES: Aplerotic, 15-23(av. 19.4 ± 0.5- 95% c.t) urn thick, ooplast 5-10 .um diam. TEMPERATURE-GROWTH RELA TIONSHIPS: Minimum 50C, optimum 25-30oC, maximum 350C. Daily growth rate on CMA at 2SoC 23.7 mm.

56 FIgs. 115-120. (115) Pythium sylvaticum: habit showing hyphae, oogonia and antheridia. (116-117) P. tracheiphilum; (116) sporangia, (117) oogonium and antheridium. (118-120) p. ultimum var ultimum; (118,119) oogonia with antheridia; (120) hyphal swelling. (Barss lf) urn).

57 MATERIAL EXAMINED: ex Lens culinaris Medik, Jenin (FCAAU 132.4, antheridial); ex soil, Nablus (FCCAU 132.1; FCCAU 132.2, FCCAU 132.3, oogonial). OCCURRENCE: Infrequently isolated from diseased roots, and rarely from soil (found in one soil).

PYTHIUM TORULOSUM Coker & Paterson, J. Elisha Mitchell scient. Soc.42:247. Figs 121-126

COLONY MORPHOLOGY: Colonies on CMA showing rosette pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-5(av. 3.5»).lm wide. SPORANGIA: Consisting of toruliod inflated branched elements, zoospores formed at 10-20"C. OOGONIA: Terminal, sometimes intercalary, smooth, 14-19(av. IS.6± 0.5-95% C.!.) .um diam. ANTHERIDIA: 1-2(- 3)/ oogonium, monoclinous originating at a distance of I-S(-12) urn from the. oognium base, occasionally diclinous. OOSPORES: Plerotic, 13.5-17.5(av. IS.I± 0.S-9S% C.I.)..um diam, wall 1-1.5 (av. l.l± 0.1-9S% C.I.)..um thick. ooplast 6-IO(av. 7.4»).lmdiam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum S·C, optimum 30' C, maximum 3l C. Daily growth rate on CMA at 25"C 9.7mm. MATERIAL EXAMINED: ex Dianthus caryophyllus L., Nablus (FCCAU 133.1; FCCAU 133.2; FCCAU 133.3). OCCURENCE: This species was isolated only from diseased roots of Dianthus caryophyllus L. It was also recorded from soil in the Lebanon (Ahrens, 1971).

58 Figs. 121-126. Pythium torulosum. (121) toruloid sporangium. (/22-126). oogonia with antheridia. (Bars= 10 urn).

59 PYTHIUM TRACHEIPHILUM Matta, Phytopath. medit. 4:51(965) Figs 116-117 OCCURRENCE: Rarely isolated from irrigated soils (found in 9% of these soils); it was not detected in nonirrigated soils.

PYTHIUM ULTIMUM VAR SPORANGIIFERUM Drechsler, Sydowia 14:107(1960) (as 'sporangiferum'),

This variety differs from var ultimum by its production of zoospores at room temperature. OCCURRENCE: Rarely isolated from soil; it was infrequently isolated from a citrus orchard near Nablus.

PYTHIUM ULTIMUM VAR ULTIMUM Trow, Ann. Bot. 15:300(1901) Figs 118-120

COLONY MORPHOLOGY: Colonies on CMA forming a diffuse pattern with some aerial mycelium. MYCELIUM: Main hyphae 3-7 (av. 4),um wide. SPORANGIA and zoospores not formed. HYPHAL SWELLINGS: Globose, intercalary, sometimes terminal, 20-35(av. 25.3± 1.7-95% c.1.) .nm diam. OOGONIA: Terminal, sometimes intercalary, smooth, 16-35 (av. 20.8± 0.5-95% C.I) JIm diam. ANTHERIDIA: 1(-3)/ oogonium, monoclinous, mostly sessile originating just below oogonium base, occasionally hypogynous or dic1inous. OOSPORES: Aplerotic, 13-24 (av. 17,0± 0.5-95% c.r.i urn diam, wall 1-1.5 (av. 1.2± 0.1-95% C.I.).llm thick, ooplast 7-14 (av. 1O± 0.4-95% C.I.).llm diam. o TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5 C, optimum 250C, maximum 30oC. Daily growth rate on CMA at 250C 14mm.

60 MATERIAL EXAMINED: ex Brassica oleracea L., var. botrytis, Ram Alla (FCCAU 123.80), Cucurbita sp., Nablus (FCCAU 123.77), Citr~s sp, Nablm (FCCAU 123.79); ex soil, Gaza (FCCAU 123.15), and many other isolates.

OCCURRENCE: This is the most frequently isolated species from diseased roots and damped off-seedlings; it was frequently isolated from 32 of the 52 host plants from which species of Pythium have been isolated in the West Bank or the Gaza Strip. It is the commonest Pythium species in this area; it is constantly present in soil <' found in all fields sampled). It was also infrequently isolated from fresh water streams. Other records from the region come from soil in Egypt (El-Helaly et al., 1972), and the Lebanon (Ahrens, 1971).

61 r PYTHIUM VANTREPOOLII V. Kouyeas, and H. Kouyeas, Annis Inst. phytopath. Benaki, N.S. 5:210(1963). Figs 127-131

COLONY MORPHOLOGY: Colonies on CMA showing a rosette pattern with some aerial mycelium. MYCELIUM: Main hyphae 2.5-5 (av. 3.3),um wide. SPORANGIA: Termihal or intercalary, consisting of catenulate, or globose to elongate unbranched outgrowths of mycelium. Zoospores produced at 10-12oc. OOGONIA: Terminal or intercalary, globose, smooth, 14-22 (av. 18.8 ± 0.6 -95% c.r.) .urn diam. ANTHERIDIA: 1(-3)/ oogonium usually monoclinous originating at 15-35 urn from oogonium base, occasionally diclinous, soon vanishing after fertilization. OOSPORES: Plerotic, wall 1.5-5 (av.2.7± 0.2 -95% c.r.) urn thick, ooplast 5-10 (av. 8.2± 0.5 -95% c.!.) urn diam. TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 50C, optimum 20-250C, maximum 300C. Daily growth rate on CMA at 25°C 8.3 mm. MATERIAL EXAMINED: ex Triticum aestivum L., El Hamra (FCCAU 123.10); ex soil, Nablus (FCCAU 125.1, FCCAU 125.2; and FCCAU 125.3), and several other isolates. OCCURRENCE: Infrequently isolated from diseased roots, and rarely from irrigated fields (found in 9% of the soils sampled). Other records of this species come from Sinapis. Secale and Triticum in Germany (Krober & Kiewnick, 1977, 1978), from Agrastis in the USA (Muse et al., 1974), from maize in Malaysia (Liu, 1977), and from soil in England (Ali, 1982).

62 Figs. 127-131. Pyihium vanterpoolii. (127) habit showing hyphae, toruloid sporangia, and oogonia.(128) toruloid sporangia. (129-131) oogonia with antheridia. (Bars: 10 urn). 63 PYTHIUM VEXANS de Bary, J. BOI. Paris 14:105-106 (1896). Figs 132-136

COLONY MORPHOLOGY: Colonies on CMA showing an indistinct chrysanthemum pattern with some aerial mycelium. MYCELIUM: Main hyphae 2.5-4 (av. 3)..um wide. SPORANGIA: Intercelary or terminal, subglobose to avoid, 15-19 (av. 16.0± 0.7-95% c.I.) urn diam, produced in water culture after 10 days, xoospores produced at 5-150C. OOGONIA: Terminal or intercalary, subglobose, 15-26 (av. 21.6± 0.8-95% c.!.) .nm diam. ANTHERIDIA: 1(- 2)/ oogonium, mostly monoclinous arising at some distance from oogonium base, rarely diclinous; antheridial cells typically bell-shaped. OOSPORES: Aplerotic, 15-21 (av. 18.8± 0.7-95% C.I.)J.lm diam, wall 1-2 (av. 1.6± 0.1 -95% c.1.) .um, ooplast 7-13 (av. 9.9± 0.5 -95% c.1.) urn diam. TEMPERATURE- GROWTH RELATIONSHIPS: Minimum 50C, Optimum 250C, maximu 35°C. Daily growth rate on CMA at 250C 10.8 mm. MATERIAL EXAMINED: ex Allium cepa L., Ram Alla' (FCCAU 126.9)m ex Sesbania aegyptiaca, Nablus (FCCA U 126.10); ex soil, Tulkarem (FCCA U 126.1), and several other isolates. OCCURRENCE: Infrequently isolated from diseased roots, and also seldom present in soil (found in 36% of the soils sampled). Other records in the region come from soil in the Lebanon (Ahrens, 1971) and from soil in Iraq (Al-Doory et al. 1959). Figs. 132-136. Pythium vexans. (132) empty sporangium with a discharge tube. (133-136) oogonia with antheridia. (Bars, IOpm).

65 PYTUIUM GROUP 'F'

OCCURRENCE: Frequently isolated from diseased roots and damped-off seedlings, rarely from soil (found in 18% of the soils sampled), and commonly isolated from fresh water streams.

PYTHIUM GROUP 'G' OCCURRENCE: Infrequently isolated from diseased roots, and rarely from soil (found in 12% of the fields sampled).

PYTUIUM GROUP 'US'

OCCURRENCE: Frequently isolated from diseased roots and damped-off seedlings; it has been isolated from seventeen host plants in the West Bank or the Gaza Strip. Constantly present in cultivated fields; it was recovered from all soils sampled.

PYTHIUM GROUP 'L'

OCCURRENCE: Infrequently isolated from diseased roots, rarely from soil (found in 6% of the soils sampled), and commonly isolated from fresh water streams.

66 V.HOST LIST A list of the vascular host plants from which species of Pythium have been isolated in the West Bank and Gaza Strip is presented below. Pythium species are indicated by numbers: (I) P. acanthicum, (2) P. anandrum, (3) P. aphanidermatum, (4) P. coloratum, (5) P. debaryanum, (6) P. dissimile, (7) P. dissotocum, (8) P. intermedium, (9) P. irregulare, (10) P. iwayamai, (II) P. lutarium, (12) P. middletonii, (13) P. myriotylum (14) P. oligandrum, (IS) P. orthogonon, (16) P. pachycaule, (17) P. paroecandrum, (18) P. parvum, (19) P. periplocum, (20) P. pulchrum, (21) P. pyrilobum, (22) P. rostratum, (23) P. splendens, (24) P. sylvaticum, (25) P. torulosum, (26) P. ultimum var ultimum, (27) P. vanterpoolii, (28) P. vexans, (29) P. group 'HS', (30) P. group 'F', (31) P. group 'L', (32) P. group 'G'.

Alcea officinalis L., hollyhock (26) (29) (30) Allium cepa L., onion (10) (14) (17) (18) (26) (28) Arachis hypogaea L., (26) Arum sp. L., 'lords and ladies' (10) (22) (26) Brassica oleracea L., var. botrytis, cauliflower (14) (26) Capsicum fructescens L., pepper (14) Caricapapaya L., papaya (26) Citrus limon (L.) Burm, lemon (22) Citrus nobilis Lour; mandarine orange (14) (26) Citrus sinensis (L.) Osbeck, sweet orange (14) (21) (22) (23) (26) • Chrysanthemum segetum L., corn marigold (26) Convolvulus arvensis L., bind weed (23) Convolulus scammonia, scamong (3) (9) (26) (23) (30) Cucumis melo L., sweet melon (26) Cucurbita pepo L., var melopero, marrow (3) (14) (23) (26) (29) Cydonia oblonga Mill, quince (29) Dahlia variabi/lis (Wild.) Desf, dahlia (29) Dianthus caryophyllus L., carnation (3) (13) (19) (25) (31) Diospyros kaki L., oriental persimon (12) (17) (29) Dryopteris filix-mas (L) Schott, male fern (26) Euphorbia pulcherrima (R. Grah.) Willd, poinsettia (10) (26) (29) Ficus elastica Roxb (26) Ficus sp (23) Jasminium fructicans L., jasmine (26)

67 Lantana sp, lantana (2) Lens culinaris Medik, lentil (4) (7) (12) (24) (26) (29) Lycopersicon esculentum Mill, tomato (10) (14) Majoranasyriaca (L.) Rafin (16) Mangifera indica L., mango (26) Malus sylvestris (L.) Mill, apple (I) (9) (26) Malva crispa, curled mallow (14) (29) Malva sp. L., mallow (20) (26) (29) (30) (31) Monstera deliciosa (20) (22) (23) (26) Notobasis syriaca (L.) Cass, Syrian plumed thistle (~2) (26) Olea europaea L., olive (10) (13) (26) (29) (30) Phaseo/us vulgaris L., common bean (14) Pothos aureus (26) (29) Prunus amygdalus (L.) Batch, almond (5) (26) Prunus avium L., plums (21) Psidium guayava L., guava (5) (9) (29) (30) Raphanus sativus L.,common radish (4) (24) (26) (30) Rosa sp, rose (8) (16) (22) (26) Schinus molle L., false pepper (3) (23) (26) Sesbania aegyptiaca, L., sesban (26) (28) Solunum me/ongona L., eggplant (3) (10) (II) (17) (26) (29) (30) So/anum rantonnetii (26) (29) (32) Solanum tuberosum L., (26) (29) Spinacia oleraceae L., spinach (15) Triticum aestivum L., wheat (10) (22) (27) (29) Viciafabae L.,broad bean (6) (9) (14) (18) (22) (26) Viola tricolor L., pansy (9) (22) (26) (30) Vitis vinifera L., grape (17) (21) (22) (30) Zea mays L., maize (26) (29) (31) VI REFERENCES

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74 VII. INDEX OF FUNGAL NAMES

Fusarium culmorum 3 Fusarium roseum 3 Hyphomyces destrucns-equi 3 Lagenidium 2 Mortierella spp 5 Nematosporangium 2 P. accantnicum 3,4, 12, 16, 17,67 P.anandrum 12, 18, I9,2~2I,67 P. aphanidermatum 3, 11, 22, 23, 67 P. coloratum 10, 24, 25, 67 P. conidiophorum 14, 24, 25 P. debaryanum 3, ~ I~ 2~2~ 67 P. deliense 3, 11,26 P. dimorphum 28 p. dissimile 11,28,29,67 P. dissotocum 30,31,67 P. echinulatum 12, 32, 33 P. entophytum 2 P. graminicola 11, 34, 35 P. hypogynum 13, 34 P. intermedium 15, 27, 36, 67 P. irregulare 3, 4, 12, 13, 36, 38, 67 P. iwayamai 13, 37, 38, 67 P. lucens 8, 14, 37 P. lutarium 8, 10, 39, 67 P. mamillatum 12, 39, 40 P. middletonii 15, 41, 42, 67 P. minor 4,8,14,41 P. monospermum 2, 10, 43, 44 P. myriotylum 3,11,43,67 P. nagaii 15, 43, 45 Pi oligandrum 3,12,46,47,67 P. othrogonon 13, 48, 67 P. pachycaule 8, 10, 48, 67 P. papillatum 10, 12, 48, 49 P. paroecandrum 13, 45, 50, 67

75 P.parvum ~~1~5~67 P. periplocum 3. II. 12.50.67 P. pulchrum 13.45.51.67 P. pyrilobum 11. 12.51.67 P. rostratum 3.4.8. 13.52.53.67 P. salpingophorum 3. 13. 14. 52. 55 P. spinosum 11. 53. 54 P. splendens 14. 15. 53. 56. 67 P. sylvaticum 4. 14. 15.56.57.67 P. torulosum 11, 58, 59, 67 P. tracheiphilum 13. 57. 60 P. ultimum var sporangiiferum 13. 60 P. ultimum var ultimum 3. 4, /3. 57. 60. 67 P. vanterpoolii 4. II. 62. 63. 67 P. vexans 13. 64. 65. 67 P. group 'F' 15,66,67 P.group 'G' 15,66,67 P. group 'US' 15,66,67 P. group'L' 15,66. 67 Rhizoctonia Solani 3 Trichoderma 3

76 ~I ~) ~IJ ~~I Pythium JI t'.~~~ 61:ii.o~I)..JI ~~ ~ )~4~.l..o Jots....k,J uk ~J bj.i tlbiJ ~~I u...:J1~ 0~1~.::J~ tl~)tl LaIJ,~ J~J u~1 ~~ J~ J):J ~J .:.UlSJ ,k~ ~~J ~I~ 0~ rJ ~1~tJ ,~I...t.;:i:.kl~1 ~l.\~J j~4 u~j oW~l:Jl ~ ~I

~J ~j..cJ1~ ~ ~lb.J:' ~ bjA JJ~ ~JJ .::J~ ~I~IJ ~ ~lS:; ~Iji 0&-uLa,k.-o~I)..JI ~J .~I ~I)..JI ~~ ~ bj.i tlbiJ ~~I u...:J1~ 4-1~ .b)Jt.:;.....J101#IJ bj.i tlbiJ ~~I u...:J1~ 4 A!i>.a.llPythium JI tl~1 t"";ji ~ rJWI ~ ~ji 0&-b.;-iji.cJ1uLaj1a...cJ1~ ;S,j ~ oW b)..lWItl~~1 LaIJ ~I ~ tl~~1 ....k,J~ 0~1 ~ ~JllI ~ u\j)l.:;>~1u~1 .1iJ.0~1 uk ~I ~I)..JI ~J ·tl~~1 ~~ w-otfa Js:~ u~~ b~ ~I)..l ~ ....k,~1 tlbiJ ~~I u...:J1~ .::J~ ~I Pythium JI tl~IJ ~~I ~I~I '"~4 Ul:i .0~1~ bj.i

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