Journal of Nematology 19(2):194-200. 1987. © The Society of Nematologists 1987. Effective Use of Marine Algal Products in the Management of Plant-Parasitic Nematodes 1 SURINDAR PARACER, 2 ARMEN C. TARJAN, s AND LYNN M. HODGSON 4 Abstract: Algal extracts were ineffective against Meloidogyne spp., Panagrellus redivivus, and Neo- aplectana carpocapsae at 1.0% aqueous concentrations, with the exception of Spatoglossum schroederi. S. schroederi killed Meloidogyne incognita, M. javanica, M. acrita, and Hoplolaimus galeatus at concentrations of 1.0, 0.75, and 0.50%. Extracts from S. schroederi at a concentration of 1.0% were ineffective against Hirschmanniella caudacrena and Belonolaimus longicaudatus. Spatoglossum schroederi, Botryocladia occidentalis, and Bryothamnion triquestrum when used as soil amendments at 0.5-1.0% concentrations (by weight) produced significant reduction of root gall development in tomato plants infected with M. incognita. Tomato plant growth was significantly improved by these algae, as well as by Caulerpa prolifera. Soil amendments of S. schroederi at concentrations of 0.5 and 1.0% significantly reduced root galling of tomato infected with M. incognita, M. arenaria, and M. javanica. Tomatoes grown in algal-soil mixture produced significantly heavier shoots and roots than plants raised in autoclaved soil. No significant differences in root-knot indices, nor in fresh and dry weights of tomato, were noted between the two concentrations of algal-soil mixture. Key words: marine algae, Meloidogyne spp., Spatoglossum schroederi, algal-soil amendments. Unique biochemical compounds from a currently used have been found to possess wide variety of marine organisms have been environmentally undesirable side effects to studied as potential pharmaceutical or bio- humans and other nontarget organisms. tidal agents (3,17,19). These organisms Pesticidal use, therefore, is increasingly be- contain elaborate secondary metabolites coming more restrictive. Use of selected that play a role in the defense of the host marine algae as biocidal agents offers a po- against predators and parasites. Marine al- tential novel approach to suppress the gae possess a wide range of compounds such nematode pests of agricultural crops. as agar, carageenan, alginic acids, caro- Chemical analyses of seaweeds indicate tenes, kainic acid, terpenes, bromine-con- that they contain all major and minor plant taining acetogenins, alkaloids, and phe- nutrients, as well as biocidal agents (18). nolic compounds (4,7). Commercial seaweed fertilizers and ex- Modern agricultural practices depend tracts have been marketed as soil additives, heavily on chemicals to control pests such conditioners, and foliar sprays. Mustard as insects, fungi, bacteria, and nematodes. plants receiving commercial seaweed ex- Because such organisms are capable of de- tract outgrew plants receiving commercial toxifying mechanisms, they have rendered liquid synthetic fertilizers (2). Liquified ineffective many of the presently used seaweed derived from AscophyUum nodosum chemicals. Additionally, many chemicals increased plant resistance to spider mites, aphids, powdery mildew, and "botrytis damping off" of seedlings (18). Seaweed Received for publication 16 December 1985. Florida Agricultural Experiment Station Journal Series products have also increased seed germi- No. 6947. These studies were conducted under Contract No. nation, plant nutrient uptake, frost hardi- R/LR-NP-1 with the Florida Sea Grant College and spon- sored by the U.S. Department of Commerce. We thank Dr. ness, and resistance to pathogenic fungi (1). J. M. Ryther, Harbor Branch Institution, for help in the Kelp derivatives were mildly nematicidal initiation of the project; and Dr. G. C. Smart, Jr., University of Florida, and Dr. R. M. Sayre, U.S. Department of Agri- and beneficial to nematode-infested citrus culture, Behsville, Maryland, for nematodes donated as test plants (20). Control of ectoparasitic nema- organisms. 2 Professor of Biology, Worcester State College, Worcester, todes, primarily Belonolaimus longicaudatus, MA 01602. on established centipede grass turf was ob- s Professor of Nematology, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611. tained from application of commercial kelp 4 Former Assistant Research Scientist, Center for Marine preparations (15). Growth of the tomato Biotechnology, Harbor Branch Institution, Fort Pierce, Flor- ida. Present address: Department of Natural Sciences, North- plants was significantly improved with a liq- ern State College, Aberdeen, SD 57401. uid concentrate of brown alga, Ecklonia 194 Marine Algal Products: Paracer et al. 195 maxima, and root-knot nematode infection TABLE 1. Species of marine algae and their ex- was reduced (5). perimental use in assaying for nematicidal activity. Antibiotics in algae, such as bromophe- Nematicidal nols, tannins, phloroglucinol, and terpe- activity noids, have been reported (6,10,12). Aque- Marine algae also have been used as an- ous Soil ex- addi- thelminthics against intestinal worms such Species tract tive as Ascaris, Oxyurus, and Trichuris (4), The red alga Digenea is recognized as an effec- Chlorophyta (green) Anadyomene menziessi Harvey + - tive agent for expulsion of Ascaris. An- Anadyomene stellata (Wolfen) thelminthic activity has also been reported C. Agardh + + for the coralline red alga, Corallina offici- Caulerpa mexicana (Sonder) nalis, and the brown algae Durvillaea, Sar- J. Agardh + - Caulerpa prolifera (Forsskal) gassum, and Ulva spp. (10). Kainic acid (KA) Lamouroux + + from Digenea simplex is a neurotoxin that Caulerpa racemosa (Forsskal) produces selective neuronal lesions and kills J. Agardh + - nerve dendrites but not axons (14). Caulerpa sertularioides (Gmelin) Howe + - This paper reports the effects of aqueous Caulerpa verticilla J. Agardh + - extracts of seaweeds on nematodes in vitro Penicillus capitatus Lamarck - + and the effects of ground seaweed amend- Cyanobacteria (bluegreen) ments on root-knot nematodes and tomato microcoleus lyngbyaceus (Kuetzing) plants in the greenhouse. Crouan + - Phaeophyta (brown) MATERIALS AND METHODS Dictyota dichotoma (Hudson) Algal extracts: Eighteen species of marine Lamouroux - + algae from Florida waters were tested for Padina vickersiae Hoyt + - Sargassum cymosum C. Agardh + + their nematicidal activity (Table 1). Each Spatoglossum schroederi (Mertens) species was field collected and transported Kutzing + + to the laboratory where it was freeze dried. Stypopodium zonale (Lamouroux) Aqueous extracts of 12 algal species were Papenfuss + - prepared as follows: Approximately 150- Rhodophyta (red) 200 g freeze-dried material was ground in Botryocladia occidentalis (Borgesen) Kylin - + chloroform (700-1,000 ml) for 20-30 sec- Bryothamnion triquetrum (Gmelin) onds in a Waring Blender and then filtered Howe - + using Whatman #1 paper. Ten-minute ex- Gracilaria mammillaris (Montagne) tractions at 35-40 C, followed by filtering, Howe + + Laurencia poitei (Lamouroux) Howe - + were repeated two more times for chlo- roform, then three times each for metha- nol and water. Aqueous extracts were freeze dried (11). ulated with a suspension of root-knot Algal powders: Freeze-dried algal mate- nematode eggs. rial was mechanically ground and sifted Nematodes: Hoplolaimus galeatus and B. through a I-ram-pore screen. Algal pow- Iongicaudatus were recovered from culti- ders thus prepared were weighed and vated soil, Hirschmanniella caudacrena ex- mixed with autoclaved field soil to obtain tracted from aquatic plant roots, Neoaplec- an appropriate algal-soil ratio by weight. tana carpocapsae juveniles obtained from Clay pots were filled with these mixtures, parasitized insects, and Panagrellus redivi- and 2-week-old tomato seedlings (Lycoper- vus cultured in oatmeal culture. sicon esculentum cv. Rutgers) were trans- Populations of the root-knot nematodes planted. One week after planting, the root M. incognita, M. javanica, M. acrita, and M. system of each tomato seedling was inoc- arenaria were propagated on tomato plants 196 Journal of Nematology, Volume 19, No. 2, April 1987 in the greenhouse at 22-35 C. To obtain were six replicates per treatment. After 1 second-stage juveniles (J2), egg masses of week, plants were inoculated with nema- root-knot nematodes were incubated in tode eggs. The algae treatments were as water in a shallow dish for 24 hours at 25 C. follows: 1) Laurencia poitei, 2) PeniciUus Root-knot egg inoculum for in vivo capitatus, 3) Bryothamnion triquestrum, 4) (greenhouse) experiments was obtained as Gracilaria mammillaris, 5) Anadyomene stel- follows: Infected roots were cleaned of de- lata, 6) Dictyota dichotoma, 7) Caulerpa pro- bris and vigorously shaken for 30 seconds lifera, 8) Botryocladia occidentalis, 9) Sargas- in 200 ml of 0.5% sodium hypochlorite so- sum cymosum, 10) Spatoglossum schroederi, 11) lution; eggs were collected on a 25-~tm-pore a mixture of 0.5% S. schroederi and 0.5% S. sieve and rinsed with tap water to remove cymosum, 12) a split treatment of S. schroe- the chemical (13). Eggs were suspended in cIeri in which 0.5% concentration was ini- 1 liter of water, and numbers in 1 ml of tially applied with 0.25% being applied 2 the suspension were counted. Between and 4 weeks later, and 13) controls con- 2,000 and 3,000 eggs in 2 ml water were sisting of soil with no added algae. placed in two small holes on opposite sides A fourth experiment was designed prin- of the base of each tomato seedling. The cipally