Nematicidal effect of Lepidium sativum on activity and reproduction of potato cyst nematode Globodera rostochiensis in soil

Abstract

In Iran, potato cyst nematode (Globodera rostochiensis) jeopardizes the traditionally high yields of potatoes in Hamadan Province in the west of Iran. Biofumigation is an eco-friendly method for integrated management of plant parasitic nematodes. In the laboratory, water extracts of water cress, fenugreek and dill similarly reduced viability of second stage juveniles after 3?h of exposure, and decreased hatching of encysted eggs to less than 1%. Pre-treatment and combined tests similarly decreased hatch. The nematicidal efficiency of top green manure of Lepidium sativum on the survival of nematode was tested on a susceptible cv in microplots. The weights of biofumigated plants increased. Anti-hatching properties of water cress applied as a biofumigant reduced hatch by average of 56%. Reproduction rates were lowered to below one, and final populations of cysts and their egg contents were reduced by nearly 60% in treated soil. Biofumigation at a 1% amendment rate was sufficient to bring about these results, which were comparable with those achieved with 2 and 3% rates. Nematicidal isothiocyanates released after incorporating glucosinolate-containing brassica plants are fully biodegradable and less toxic than their synthetic equivalents, and their use is considered a safer alternative to soil fumigants such as methyl bromide.     

Potential for biological control of Heterodera schachtii by Pochonia chlamydosporia var. chlamydosporia on sugar beet

The biological control potential of an isolate of Pochonia chlamydosporia var. chlamydosporia against Heterodera schachtii was examined by assessing the percentage of females and cysts that became infected on water agar, the effect of culture filtrate on juvenile mobility, and the effects of the fungus on the final population of the nematode on sugar beet under greenhouse conditions. After 3 weeks at 20°C, 74 and 95% of the eggs within cysts and females, respectively, were colonised by the fungus on water agar. The full concentration of the fungal filtrate from cultures in malt extract broth killed only 12% of the juveniles after 24 h at 25°C. In the greenhouse experiment, adding 16,000 chlamydospores of the fungus per gram of soil as either colonised barley grains or spores reduced the final number of females on roots of sugar beet by 50 and 66%, respectively, after 3 months. The reproduction factor was reduced to ×2 in spore-treated soil compared with ×5 in the untreated control, and 18% of the eggs in spore-treated soil were colonised by fungal mycelium. Generally, P. chlamydosporia var. chlamydosporia was more efficient at reducing the nematode population when applied as spores without any substrate than when used as colonised barley grains.     

Seed treatment and soil drench with dl-β-amino butyric acid for the suppression of Meloidogyne javanica on tomato

Due to the recent environmental concerns, increasing amounts of research have been diverted to investigating natural products for the control of nematodes. dl-β-Amino butyric acid (BABA) could play a part in limiting nematode damage to plants. In this study, different concentrations of BABA were used as soil drench and seed treatment to determine if they can control Meloidogyne javanica on tomato. In an in vitro test, BABA did not impair mobility of second-stage juveniles of the nematode but 10 and 25 mg/l concentrations reduced hatch. Both of the application methods tested (drenching soil and/or pre-treating seeds with 25 mg/l of BABA) for the treatment of nematode infested tomato plants reduced the numbers of galls and egg masses by 82 %; nematode reproduction rates on these plants were reduced to one and, compared with untreated control plants, final nematode density was decreased by nearly 87 %. Increasing BABA concentrations of the treatment solutions to 200 and 500 mg/l resulted in further reduction in nematode damage and reproduction on treated plants, although the differences between the concentrations were not significant. Compared with untreated tomato, gall and egg mass production were decreased by an average of 92 %, and reproduction rates were held below one by both the 200- and 500-mg/l BABA rates. When seeds pretreated with 25 mg/l were also soil drenched with three BABA concentrations, the effects were slightly greater than when each method was used alone. Treated plants showed slight improvement in growth and weight.