JOURNAL OF NEMATOLOGY VOLUME 21 APRIL 1989 NUMBER 2

Journal of Nematology 21(2):147-157. 1989. © The Society of Nematologists 1989. Pineapple Research in Hawaii: Past, Present, and Future 1 E. P. CASWELL AND W. J. APT*

Abstract: The first written record of pineapple in Hawaii is from 1813. In 1901 commercial pineapple production started, and in 1924 the Experiment Station for pineapple research was established. Nematode-related problems were recognized in the early 1900s by N. A. Cobb. From 1920 to approximately 1945 nematode management in Hawaiian pineapple was based on fallowing and crop rotation. During the 1920s and 1930s G. H. Godfrey conducted research on pineapple nematode management. In the 1930s and 1940s M. B. Linford researched biological control and described several new species of including . In 1941 nematology and nematode management were advanced by Walter Carter's discovery of the first economical soil fumigant for nematodes, D-D mixture. Subsequently, DBCP was discovered and developed at the Pineapple Research Institute (PRI). Since 1945 soil fumigation has been the main nematode man- agement strategy in Hawaiian pineapple production. Recent research has focused on the develop- ment of the nonvolatile nematicides, their potential as systemic nematicides, and their application via drip irrigation. Current and future research addresses biological and cultural alternatives to nematicide-based nematode management. Key words: Hawaii, history, nematicide, nematode management, pineapple.

The history of pineapple nematology in United States (46). Pineapple was planted Hawaii over the past 70 years reflects im- on approximately 14,570 hectares in 1986, portant developments in the science of and the fresh market and processed com- nematology during that time. This histor- modity value was $242 million (3). ical review of Hawaiian pineapple-nema- Pineapple Was first reported in Hawaii tode research and the individual scientists in 1813, but it had probably been present involved in that work encompasses the in Hawaii for some time before then (10). changes in nematode management strate- The Hawaiian Pineapple Company, later gies employed in Hawaiian pineapple pro- to be Dole Company, was founded in 1901, duction. and the Hawaiian Pineapple Packers' As- sociation was formed in 1912. PINEAPPLE IN HAWAII Pineapple research in Hawaii: Research On Hawaii consists of 132 islands, reefs, and pineapple production was initiated through shoals and is the southernmost of the an arrangement between the Hawaiian Pineapple Packers' Association (HPPA) and the Hawaiian Sugar Planters' Association Received for publication 29 January 1988. Symposium paper presented at the annual meeting of the (HSPA) in 1914. In 1916 it was discovered Society of Nematologists, 19-22 July 1987, Honolulu, HI. that iron sulfate sprays significantly im- Journal Series No. 3245 of the College of Tropical Agricul- ture and Human Resources, University of Hawaii, Honolulu, proved pineapple growth and organized, HI. scientific research on pineapple produc- 2 Assistant Researcher and Researcher, respectively, 3190 Maile Way, Department of Pathology, University of tion was initiated. In 1924 an experiment Hawaii, Honolulu, HI 96822-2279. station for pineapple research was estab- We thank the Governor's Agricultural Coordinating Com- mittee of the State of Hawaii for financial support and Calvin lished, marking the beginning of a scien- Oda of Del Monte Company and David Williams of Maul tific approach to growing pineapple--an Land & Pineapple Company for access to unpublished records from the Pineapple Research Institute on pineapple nema- approach that led to the formation of an tology in Hawaii. agricultural industry based on scientific re-

The JOURNAL OF NEMATOLOGY for January (21:1-146) was issued 29 January 1989. 147 148 Journal of Nematology, Volume 21, No. 2, April 1989

Standard cultural practices including 2-year fallow periods with six cultivations during the period, application of fertilizer and the use of Eckart paper mulch, hand planting of crowns or slips through the mulch paper, and fertilization with iron sulfate sprays were used to alleviate plant stresses as early as 1925. Until the advent of soil fumigation with D-D mixture in 1945, management of plant-parasitic nematodes was by fallowing and crop ro- tation. The use of mulch paper, hand planting, and machine-assisted hand har- vesting continues today.

THE NEMATOLOGISTS Several nematologists have conducted research in Hawaii. A summary of their major contributions is presented with ref- erences to their work. In some instances unpublished reports of the director of the PRI are quoted. Nathan Augustus Cobb: Cobb accepted a position with the Hawaii Sugar Planters' FxG. I. George H. Godfrey, employed as nema- tologist by the PRI from 1926 to 1932. Association in 1905 and remained in Ha- waii until 1907 (6). He hired E. M. Grosse and W. E. Chambers as illustrators, and search. The formal name of the Experi- Chambers, with Cobb for approximately ment Station was changed in 1933 to the 15 years, developed a solid reputation as a Experiment Station of the Pineapple Pro- scientific illustrator. ducers' Cooperative Association, and was During his time in Hawaii, Cobb did not renamed in 1941 as the Pineapple Re- investigate pineapple nematodes, but his search Institute (PRI) of Hawaii. research on nematode parasites of sugar- Nematodes on pineapple in Hawaii: The cane established the presence of Meloido- first disease recognized in Hawaiian - gyne javanica (Heterodera radicicola sensu apple was "wilt." Nematodes were be- latu) and the general importance of plant- lieved to have a role in the wilt disease, but parasitic nematodes in Hawaii. His re- the etiology of the disease was poorly search established basic information on the understood and insects, nematodes, and life cycle of root-knot nematode, including fungi were thought to be involved in the the observation that it could not survive disease (7). The importance of nematodes temperature extremes. to pineapple production was recognized in George H. Godfrey: A nematode survey of the early 1920s. From about 1920 to 1950 the pineapple growing regions in 1924 es- the root-knot nematode, Meloidogynejavan- tablished a correlation between the occur- ica (Treub, 1885) Chitwood, 1949, was the rence of root-knot nematode and pine- primary nematode problem. Since 1950 the apple wilt: "the area in which the nematode reniform nematode, Rotylenchulus renifor- galls occur on the roots of the cor- mis (Linford and Oliveira, 1940), has been responds with the area in which the pine- the key nematode problem. Crop failures apples are wilting." Such observations were not uncommon in nematode-infested prompted the Experiment Station Direc- areas from 1920 to 1945. tor in 1926 to write "it became clear that Pineapple Nematology: Caswell, Apt 149

FIG. 2. Nematodeextraction apparatus from the lab of G. H. Godfrey at the PRI consisting of a set of nested Tyler sieves. Movement of water through the screens was assisted by vacuum. something decisive should be done about understood today. His work established the one of our most serious enemies, the root- importance of plant-parasitic nematodes in infesting nematodes." Consequently, a Hawaiian pineapple. hematologist, G. H. Godfrey (Fig. 1), was He conducted research on techniques for hired by the Experiment Station in 1926. studying root-knot nematodes in plants Godfrey was hired to serve as head of (13,16), the use of indicator plants to assess the Nematology Section of the Experiment nematode population densities in soil (14), Station and to investigate nematode prob- nematodes other than root-knot that might lems. The Nematology Section consisted be problems in pineapple or other plants of Godfrey and Ms. Helene Morita, a tech- (12), the use and efficacy of chloropicrin, nician. At the time Godfrey was hired, the carbon bisulfide, and hydrocyanic gas as most effective nematode control measure fumigants (15,17,26), the influence of root- used in Hawaii was extended (2 years) fal- knot on pineapple growth (18,21), root- lowing. Godfrey was aware of nematode- knot nematode development (24), the use control strategies being investigated in Eu- and efficacy of trap crops (20,23), and the rope such as the use of trap crops, flooding, influence of pH, moisture, and tempera- desiccation, natural enemies, and applica- ture on the root-knot nematode life cycle tion of chemical soil treatments (including (19,22,25,29). He was also aware of the ammonia, ammonium sulfate, carbon bi- value of looking for "escapes" in the field sulfide, cyanide, formalin, and others). as a means of identifying nematode resis- Godfrey's research in Hawaii covered tance in pineapple. many areas of nematology and plant pa- Godfrey, a good soil ecologist, noted in thology, addressing aspects of nematode a 1927 progress report: "We must not fail biology and ecology that are still poorly to recognize the importance of becoming

...... J! ...... 150 Journal of Nematology, Volume 21, No. 2, April i989

FIG. 3. Juliette Oliveira, junior nematologist at FIG. 4. Walter Carter, entomologist at the PRI, the PRI, worked with G. H. Godfrey and M. B. Lin- discovered the nematicidal activity of D-D mixture in ford. Photograph ca. 1938. 1941. Photograph ca. 1944. thoroughly familiar, by this means (study- Carl Schmidt (Fig. 5) in 1931. Carter and ing soil ecology), with the structure as well Schmidt were appointed to the Entomol- as the life and habits of the organisms with ogy Department. which we are concerned. Furthermore, this Hagan worked with Godfrey on several work must be done to pave the way for projects, including assessing the effect of what we plan to do ultimately in the way root-knot on plant growth (21), influence of developing the proposition of biological ofpH on root-knot nematode (19), efficacy control." Godfrey was aware that Monon- of trap crops (20), and influence of soil chus might play a role in biological control, temperatures on root-knot nematode (27). and included it in his research plans. The He also worked withJ. L. Collins on nema- nematode extraction apparatus used by tode resistance in pineapples (11,28). They Godfrey featured a set of nested Tyler focused on root-knot nematode resistance sieves (Fig. 2). and identified two varieties ("Wild Bra- Godfrey was released by the Experiment zil"---Ananas ananassoides, and Lot 250, a Station in 1932, primarily as a result of the Cayenne x Wild Brazil hybrid) that had depression. tolerance to root-knot nematode damage. Harold R. Hagan: Originally trained in They did not assess nematode reproduc- entomology, Hagan was hired into the tion on the varieties, limiting their studies Nematology Section of the Experiment to effects of the nematode on plant growth. Station in 1929. His primary responsibility Attempts to identify and incorporate was field nematology. Related appoint- nematode resistance into commercial cul- ments during this time were Juliette Oli- tivars continued through the 1930s and into veira (Fig. 3) as a junior nematologist in the early 1940s with little success. 1928, Walter Carter (Fig. 4) in 1930, and Hagan, like Godfrey, was released from Pineapple Nematology: Caswell, Apt 151

FIG. 5. Carl Schmidt, entomologist at the PRI, FIG. 6. Maurice Linford, plant pathologist at the discovered the nematicidal activity of DBCP. Photo- PRI, pioneered work on biological control of plant- graph ca. 1938. parasitic nematodes by soil fungi. Photograph ca. 1938. the Experiment Station in 1932 because of Pathology Department in 1929, Linford's the depression. In addition, Walter Carter initial work focused on plant pathogens, had suggested that the "wilt" disease was including suspected virus diseases. By 1935 caused by mealy bugs and that nematodes Linford (Fig. 6) had established that fungi were of minor importance as agents in- parasitic on nematodes were present in ducing pineapple disease (7). The Experi- pineapple fields. Over the years he contin- ment Station Director in 1932 was an ento- ued to study the role of soil fungi in sup- mologist, who noted "information is pressing nematode populations and the accumulating to show that nematodes have possibility of effective and manageable bi- much less effect on the welfare of the plant ological control (31,32,34,42,44), work that than had been supposed" and "there is no was continued into the mid-1950s at PRI general systemic effect upon the pineapple (30). Linford also worked on methods for plant due to the activity of nematodes on observing nematodes and their antagonists its roots." In response to these statements, within root systems (36,39), demonstrated Magistad and Oliveira demonstrated that that root-knot nematodes could infect root-knot nematode infection was delete- leaves and shoots of plants (37), and stud- rious to pineapple growth by decreasing ied nematode feeding behavior (33,35,38). the average total root length, reducing In 1936 Francis Yap (Fig. 7), a technician plant growth rate, and decreasing the ab- at the Experiment Station, observed a sorption of nitrogen (45). Nevertheless, the nematode on the roots of cowpea. The Nematology Section was closed in 1934, nematode did not cause galling, but it could and its remaining personnel were moved be detected by small masses of soil clinging into the Department of Plant Pathology. to the gelatinous matrix of females embed- Maurice Blood Linford: Hired to head the ded in roots (Fig. 8). This nematode was 152 Journal of Nematology, Volume 21, No. 2, April 1989

the late 1950s publication of PRI research in the literature was discouraged and any publication required permission of the di- rector. Walter Carter: In 1930 Carter (Fig. 4), an entomologist, was hired by the Exper- iment Station. As Head of the Entomology Department at the Experiment Station and the PRI from 1932 to 1961, he had a strong influence on Hawaiian nematology. When economic conditions became difficult for the Experiment Station in the early 1930s, the Nematology Department was disband- ed, and Carter's arguments concerning the etiology of wilt disease (7) influenced the i perceived importance of nematode dis- i ii, eases. He renamed the wilt disease "mealy- i bug wilt" as mealy-bugs were associated ! i ¸: ~ •i: •••• with wilted plants and seemed able to trans- mit the disease. Carter wrote: "Evidence is !}i~ ...... • • • S • •)' •••" • • accumulating, however, from a large series of control experiments, as well as from commercial fields that have been consis- FIG. 7. Francis Yap, technician at the PRI, was the tently treated for mealy-bug control, that first to observe the presence ofRotylenchulus reniformis mealy-bug wilt is the major factor in failure on the roots of cowpeas. Photograph ca. 1938. of pineapples in Hawaii and that other fac- tors only operate in extremely localized areas and sometimes then only under ab- subsequently described by Linford and normal weather conditions" (7). Carter Oliveira as Rotylenchulus reniformis (40), a emphasized that mealy-bugs were the most nematode with a rather wide host range important, if not only, pest problem in (43). During the early 1940s the potential pineapple. This information was influen- damage by reniform nematode was stud- tial because wilt had been the pineapple ied, along with its ability to withstand des- industry's major problem since the early iccation. The nematode was pathogenic on 1920s. certain host plants, and could tolerate des- Ironically, Carter eventually established iccation much better than could root-knot the importance of nematodes as limiting nematodes. Linford et al, also described factors in plant growth with his discovery Paratylenchus minutus, a parasite of pine- of the nematicidal activity of 1,2-dichlo- apple, in 1949 (41). During this time the ropropane, 1,3-dichloropropene (D-D) Plant Pathology Department investigated mixture in 1941 (8,9). He was examining the possible occurrence of races of the root- the influence of soil fumigants on mealy- knot nematode on Oahu. Linford resigned bug wilt and in early 1940 was informed in September of 1949 and moved to the that Shell Company had liquid compounds University of Illinois. available that were byproducts of the pro- Publication of research was opposed by duction of allyl chloride. One compound some pineapple industry personnel in the was not pure and would present a disposal 1930s. The station director vigorously de- problem when manufacture of other com- fended the need to publish results of re- pounds was increased. That compound was search done at the Experiment Station, and D-D. Field trials including D-D were con- Linford continued to publish his work. By ducted in several pineapple fields in 1940, Pineapple Nematology: CasweU, Apt 153

FIG. 8. Rotylenchulusreniformis on plant roots showing the characteristic soil adhering to the egg masses of the female nematodes. and an increased growth response was seen in producing nematode gall-free (8). The reason for the growth response plants as well as carrots was demonstrated was not clear, but increased root growth conclusively." was observed in treated plots. In 1943 the acting director of PRI not- The influence of D-D on nematodes was ed: "D-D mixture is most likely to fulfill its clearly demonstrated in another set of plots promise of being an answer to the need for about which Carter wrote: "The use of a cheap soil fumigant which can be applied D-D which definitely demonstrated its ne- as an insurance measure in any field where maticidal value against root-knot nema- failure due to soil organisms is likely to be tode came about in another matter. Prior a factor." By 1944 the toxicity of D-D to to Dec. 7, 1941, elaborate plans had been root-knot nematode eggs, even if the eggs made to provide food in the event of a siege were within roots, was recognized. In ad- of the Islands and the writer was assigned dition, Linford's work suggested that D-D the duty of organizing this among pine- was not overly toxic to nematode-destroy- apple plantations. Mr. Colin Lennox was ing fungi. my opposite number in the Sugar Experi- In 1943 Carter applied for a patent on ment Station and he operated small variety D-D mixture for use as a soil fumigant to trials on the Station Grounds. With his co- rid agricultural soils of deleterious organ- operation, tests were set up in tomato and isms. The patent was awarded in 1950. The other vegetable plots to ascertain the efficacy of D-D as a soil fumigant in pro- growth stimulation effects then showing up moting plant growth (Fig. 9) revolution- in the pineapple field plots. It so happened ized nematology. Shell Oil Company in- that the ground was heavily infested with creased production of D-D mixture in root-knot nematode and the effect of D-D response to the demand for the fumigant 154 Journal of Nematology, Volume 21, No. 2, April 1989

Fz~. 9. Improved growth in pineapple as a result of nematode control by preplant soil fumigationwith D-D mixture. Plants on the right were grown in fumigated soil. Photograph ca. 1950. by the Hawaiian pineapple industry. Soil During 1943-46, the potential of eth- fumigation assisted in the eventual differ- ylene dibromide (EDB) as a general soil entiation of wilt symptoms resulting from fumigant was also studied by Carter and nematode induced moisture stress and wilt Schmidt, with good success. By 1950 EDB associated with mealy-bugs. was established as an effective soil fumi- Carter summarized the ramifications of gant; it was used until it was removed from the discovery of D-D, noting: "It will be U.S. markets in September of 1983, generally agreed that the advent of D-D The focus of nematology research at PRI ushered in a new phase of practical plant and the culture of pineapple in Hawaii were protection, initially with a profound effect changed dramatically by Carter's discov- on the maintenance of the pineapple in- ery. The age of nematicides had arrived, dustry in Hawaii; it contributed to a long and many potential fumigants were soon overdue support for the expansion of being screened at the PRI. By the late 1940s Nematology as a specialized branch of zo- preplant soil fumigation for nematode con- ology; it intensified the research programs trol was standard industry practice. of primary chemical producers leading to Carter retired from the PRI in 1962. the development of practical alternatives Carl T. Schmidt: Hired by the Experi- as well as to many basic contributions to ment Station as an entomologist in 1931, soil microbiology; and last but not least, it Schmidt (Fig. 5) worked at PRI until he is contributing to the alleviation of the was released in 1963. He was responsible problem of a hungry world." D-D re- for the discovery of the soil fumigant 1,2- mained an effective soil fumigant, widely dibromo-3-chloropropane (DBCP). He used in the Hawaiian pineapple industry, claimed a patent with the U.S. Patent Of- until its U.S. registration was revoked in fice in 1954 for the use of DBCP as a March of 1984. method of treating soil to improve its plant- Pineapple Nematology: CasweU, Apt 155 growing properties. The patent was award- WalterJ. Apt: During 1958 and 1959 Apt ed in 1960. DBCP was unique as a soil fu- served as a consultant nematologist with migant, providing effective nematode con- the Hawaii Sugar Planters Association in trol at relatively low application rates with Honolulu. In 1963 he returned to Hawaii the capacity for use as a postplant fumi- and the PRI where his research program gant. included the evaluation and development DBCP became a widely used, effective of effective nematode management strat- nematicide until it was removed from U.S. egies using volatile and nonvolatile nema- markets in 1977. A testament to the im- ticides. He is credited with being the first portance of DBCP to Hawaiian pineapple individual to design a nematode manage- is that Maui Pineapple Co. obtained a spe- ment program based upon the systemic cial-use permit allowing use of DBCP on properties of foliar-applied fenamiphos the island of Maui until 1984. (50). He also has continued work initiated E. J. Anderson: Hired as a plant pathol- by Linford on the ability of reniform and ogist by the PRI in 1945, Anderson was root-knot nematodes to withstand desic- named Department Head when Linford cation (4,48,49). left in 1949, and he remained there until In 1973, the PRI was closed and Apt was the PRI eliminated the Department in appointed Professor of Plant Pathology at 1966. During his tenure at the PRI he was the University of Hawaii. He has pursued responsible for work on the development techniques for applying nematicides of fumigant usage patterns, specifically through drip systems (5) and has continued placement depth and application rates for to investigate desiccation tolerance in root- D-D, EDB, and DBCP and the efficacy of knot and reniform nematodes. mulches in promoting fumigant action (1). His work clearly demonstrated the toxicity THE PRESENT of D-D to nematodes. He investigated the Current pineapple plantation practices effect of soil moisture on the efficacy of include 6-12-month fallow periods with all fumigation and showed that D-D and EDB fields receiving preplant fumigation with were more effective in moist than in dry dichloropropene. Oxamyl and fenamiphos soils. are labeled for use through drip irrigation During the mid-1950s the importance of and for foliar applications. These may be reniform nematode was increasing. Fields applied to supplement preplant soil fumi- with problem-level populations of reni- gation or used alone (47). form increased in frequency on all the is- The current pineapple nematology re- lands, and Anderson was responsible for search program in Hawaii is focusing on the sampling program to assess infestation development of integrated nematode man- levels. He developed rapid methods for de- agement strategies through balanced use termining the numbers of nematodes in a of biological, cultural, and nematicide- sample (2). During the same time period based management practices. This ap- soil acidity was becoming a problem in many proach was prompted by the loss of the s0il fields; some fields recorded a pH as low as fumigants DBCP, EDB, and D-D mixture, 3.8. The increasing importance of the re- as well as increasing concern with environ- niform nematode during the 1950s has mental contamination and the industry's been attributed, in part, to increasing soil reliance on preplant soil fumigation using acidity (47). 1,3-dichloropropene for nematode man- John D. Radewald: Appointed nematol- agement. ogist at PRI in 1960, Radewald initiated work on the efficacy of fumigants and the THE FUTURE ability of reniform nematode to withstand The future of pineapple and pineapple- moisture stress. He remained in Hawaii for nematode management in Hawaii is un- 3 years. certain. Integrated management ap- 156 Journal of Nematology, Volume 21, No. 2, April 1989 proaches, if successful, will allow judicious 17. Godfrey, G. H. 1935. Experiments on the con- use of nematicides in combination with cul- trol of the root-knot nematode in the field with chlo- tural practices and biological control ropicrin and other chemicals. Phytopathology 25:67- 90. agents. Such an approach would depend 18. Godfrey, G. H. 1936. The pineapple root sys- on developing a firm understanding of the tem as affected by the root-knot nematode. Phyto- biology and ecology of root-knot and re- pathology 26:408-428. 19. Godfrey, G. H., and H. R. Hagan. 1933. In- niform nematodes in Hawaiian pineapple fluence of soil hydrogen-ion concentrations on infec- production, a goal stated by Godfrey more tion by Heterodera radicicola (Greef). Soil Science 35: than 50 years ago. 175-184. 20. Godfrey, G. H., and H. R. Hagan. 1934. A LITERATURE CITED study of the root-knot nematode trap crop under field 1. Anderson, E.J. 1956. Comparison of initial kills conditions. Pbytopathology 24:648-658. and subsequent increase of nematode populations fol- 21. Godfrey, G. H.,andH. R. Hagan. 1937. Some lowing soil fumigation. Phytopathology 46:634 measurements of detrimental effects of the root-knot (Abstr.). nematode on the pineapple plant. Phytopathology 27: 2. Anderson, E. J., and I. Yanagihara. 1955. A 515-530. method for estimating numbers of motile nematodes 22. Godfrey, G. H., and H. M. Hoshino. 1933. in large numbers of soil samples. Phytopathology 45: Studies on certain environmental relations of the root- 238-239. knot nematode, Heterodera radicicola. Phytopathology 3. Anonymous. 1986. Statistics of Hawaiian ag- 23:41-62. riculture. Hawaii Agricultural Statistics Service, Ho- 23. Godfrey, G. H., and H. M. Hoshino. 1934. nolulu, HI. The trap crop as a means of reducing root-knot nema- 4. Apt, W.J. 1976. Survival ofreniform nematode tode infestation. Phytopathology 24:635-647. in desiccated soils. Journal of Nematology 8:278 24. Godfrey, G. H., and J. Oliveira. 1932. The (Abstr.). development of the root-knot nematode in relation 5. Apt, W.J., and E. P. Caswell. 1988. Application to root tissues of pineapple and cowpea. Phytopathol- of nematicides via drip irrigation. Annals of Applied ogy 22:326-348. Nematology (Journal of Nematology 20, Supple- 25. Godfrey, G. H., J. M. Oliveira, and E. B. H. ment) 2:1-10. Gittel. 1933. The duration of life of the root knot 6. Blanchard, F. C. 1957. Nathan A. Cobb, bot- nematode, Heterodera radicicola, in soils subjected to anist and zoologist, a pioneer scientist in Australia. drying. Soil Science 35:185-195. Asa Gray Bulletin 3:205-272. 26. Godfrey, G. H., J. M. Oliveira, and H. M. 7. Carter, W. 1933. The pineapple mealy bug, Hoshino. 1934. Increased efficiency ofchloropicrin Pseudococcus brevipes, and wilt of pineapple. Phyto- for nematode control with better confinement of the pathology 23:207-242. gas. Phytopathology 24:1332-1346. 8. Carter, W. 1943. A promising new soil amend- 27. Hagan, H. R. 1933. Hawaiian pineapple field ment and disinfectant. Science 97:383-384. soil temperatures in relation to the nematode Heter- 9. Carter, W. 1945. Soil treatment with special odera radicicola (Greef) Muller. Soil Science 36:83- reference to fumigation with D-D mixture. Journal 95. of Economic Entomology 38:35-44. 28. Hagan, H. R., andJ. L. Collins. 1935. Studies 10. Collins, J. L. 1968. The pineapple. London: on varietal resistance of pineapple plants. Part II. Plant Leonard Hill Books. resistance to Heterodera marioni (Cornu) Goodey. Jour- 11. Collins, J. L., and H. R. Hagan. 1932. Nema- nal of Heredity 26:35-46. tode resistance of pineapples: Varietal resistance of 29. Hoshino, H. M., and G. H. Godfrey. 1933. pineapple roots to the nematode Heterodera radicicola Thermal death point of Heterodera radicicola in rela- (Greef) Muller. Journal of Heredity 23:459-511. tion to time. Phytopathology 23:260-270. 12. Godfrey, G. H. 1929. A destructive root dis- 30. Klemmer, H. W., and R. Y. Nakano. 1964. A ease of pineapples and other plants due to Tylenchus semi-quantitative method of counting nematode-trap- brachyurus, n. sp. Phytopathology 19:611-629. ping fungi in soil. Nature 203:1085. 13. Godfrey, G. H. 1931. Some techniques used 31. Linford, M. B. 1937. Stimulated activity of in the study of the root-knot nematode, Helerodera natural enemies of nematodes. Science 85:123-124. radicicola. Phytopathology 21:323-329. 32. Linford, M. B. 1937. The feeding of hollow- 14. Godfrey, G. H. 1934. Indicator plants for spear nematodes on other nematodes. Science 85: measuring soil populations of the root-knot nema- 295-297. tode, Heterodera marioni (Cornu) Goodey. Soil Science 33. Linford, M. B. 1937. The feeding of the root- 38:3-27. knot nematode in root tissue and nutrient solution. 15. Godfrey, G. H. 1934. The confinement of Phytopathology 27:824-835. chloropicrin and other gases for fumigation purposes. 34. Linford, M. B. 1937. The feeding of some Phytopathology 24:1366-1373. hoUow-stylet nematodes. Proceedings of the Helmin- 16. Godfrey, G. H. 1935. The demonstration of thological Society of Washington 4:41-46. plant-parasitic nematodes in host tissues. Phytopa- 35. Linford, M. B. 1937. Notes on the feeding of thology 25:1026-1030. 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