Timper Patricia, Davis Richard F, Tillman P Glynn
USDA ARS, Crop Protection and Management Research Unit, PO Box 748, Tifton, GA 31793.
J Nematol. 2006 Mar;38(1):83-9.
Substantial reproduction of Meloidogyne incognita on winter cover crops may lead to damaging populations in a subsequent cotton (Gossypium hirsutum) crop. The amount of population increase during the winter depends on soil temperature and the host status of the cover crop. Our objectives were to quantify M. incognita race 3 reproduction on rye (Secale cereale) and several leguminous cover crops and to determine if these cover crops increase population densities of M. incognita and subsequent damage to cotton. The cover crops tested were 'Bigbee' berseem clover (Trifolium alexandrinum), 'Paradana' balansa clover (T. balansae), 'AU Sunrise' and 'Dixie' crimson clover (T. incarnatum), 'Cherokee' red clover (T. pratense), common and 'AU Early Cover' hairy vetch (Vicia villosa), 'Cahaba White' vetch (V. sativa), and 'Wrens Abruzzi' rye. In the greenhouse tests, egg production was greatest on berseem clover, Dixie crimson clover, AU Early Cover hairy vetch, and common hairy vetch; intermediate on Balansa clover and AU Sunrise crimson clover; and least on rye, Cahaba White vetch, and Cherokee red clover. In both 2002 and 2003 field tests, enough heat units were accumulated between 1 January and 20 May for the nematode to complete two generations. Both AU Early Cover and common hairy vetch led to greater root galling than fallow in the subsequent cotton crop; they also supported high reproduction of M. incognita in the greenhouse. Rye and Cahaba White vetch did not increase root galling on cotton and were relatively poor hosts for M. incognita. Only those legumes that increased populations of M. incognita reduced cotton yield. In the southern US, M. incognita can complete one to two generations on a susceptible winter cover crop, so cover crops that support high nematode reproduction may lead to damage and yield losses in the following cotton crop. Planting rye or Meloidogyne-resistant legumes as winter cover crops will lower the risk of increased nematode populations compared to most vetches and clovers.
南方根结线虫在冬季覆盖作物上大量繁殖可能会导致后续棉花作物中有害虫口数量增加。冬季期间虫口数量的增长幅度取决于土壤温度和覆盖作物的寄主状况。我们的目标是量化南方根结线虫3号小种在黑麦和几种豆科覆盖作物上的繁殖情况，并确定这些覆盖作物是否会增加南方根结线虫的虫口密度以及对后续棉花造成损害。所测试的覆盖作物有‘Bigbee’埃及三叶草（Trifolium alexandrinum）、‘Paradana’巴拉那三叶草（T. balansae）、‘AU Sunrise’和‘Dixie’绛三叶（T. incarnatum）、‘Cherokee’红三叶（T. pratense）、普通毛苕子和‘AU Early Cover’毛苕子（Vicia villosa）、‘Cahaba White’巢菜（V. sativa）以及‘Wrens Abruzzi’黑麦。在温室试验中，埃及三叶草、Dixie绛三叶、AU Early Cover毛苕子和普通毛苕子上的产卵量最高；巴拉那三叶草和AU Sunrise绛三叶上的产卵量中等；黑麦、Cahaba White巢菜和Cherokee红三叶上的产卵量最少。在2002年和2003年的田间试验中，1月1日至5月20日期间积累的热量单位足以使线虫完成两代繁殖。AU Early Cover毛苕子和普通毛苕子在后续棉花作物上导致的根瘤比休闲地更多；它们在温室中也支持南方根结线虫的大量繁殖。黑麦和Cahaba White巢菜不会增加棉花上的根瘤，并且是南方根结线虫相对较差的寄主。只有那些增加南方根结线虫虫口数量的豆科植物会降低棉花产量。在美国南部，南方根结线虫在易感的冬季覆盖作物上可以完成一代至两代繁殖，因此支持线虫大量繁殖的覆盖作物可能会导致后续棉花作物受到损害并造成产量损失。与大多数苕子和三叶草相比，种植黑麦或抗南方根结线虫的豆科植物作为冬季覆盖作物将降低线虫虫口数量增加的风险。
