Received for publication 21 February 1978. 1Broom's Barn Experimental Station, Higham, Bury St. Edmunds, Suffolk, England. 2 Department of Nematology, University of California, Riverside, California 92521. 3Farm Advisor, Cooperative Extension, Santa Maria, California 93456. 4 Farm Advisor, Cooperative Extension, El Centro, California 92243. Much of this work was done while the senior author was...

Field and greenhouse experiments showed that yield losses of sugarbeet, Beta vulgaris, did not occur in soil infested with fewer than eight Heterodera schachtii eggs/g soil. However, larger population densities greatly reduced sugarbeet yield. In the field experiment, the yield in microplots inoculated with more than 64 eggs/g soil was less than 20% of yields in uninoculated microplots. Neverth...

Cyst nematodes are sedentary endoparasites of plants which cause important economic losses worldwide. New nematode control measures needed since the removal effective chemical nematicides from market due to their negative impact on environment and human health. Induced hatching second-stage juveniles in absence host plant using root exudates, also named “suicide hatching”, could be a sustainabl...

Studying wild pathogen populations in natural ecosystems offers the opportunity to better understand the evolutionary dynamics of biotic diseases in crops and to enhance pest control strategies. We used simulations and genetic markers to investigate the spatial and temporal population genetic structure of wild populations of the beet cyst nematode Heterodera schachtii on a wild host plant speci...

Histological changes in roots of Beta vulgaris cultivar 'USH9A' resulting from infection of Meloidogyne hapla alone, Heterodera schachtii alone, or infection by both species on one feeding site were studied. Anatomical changes caused by M. hapla infection were characterized by regions of hypertrophy and hyperplasia. Giant cells were formed within the stele and varied in numbers from 4-7/feeding...

A filamentous, nonsporulating fungus, designated Arkansas Fungus 18 (ARF18), was isolated from 9 of 95 populations of Heterodera glycines, the soybean cyst nematode, in Arkansas. In petri dishes, ARF18 parasitized 89% of H. glycines eggs in cysts. The fungus also infected eggs of Meloidogyne incognita and eggs in cysts of Cactodera betulae, H. graminophila, H. lespedezae, H. leuceilyma, H. scha...