The Study Of Mode Of Action And Application Technology Of Fosthiazate To Cereal Cyst Nematode(Heterodera Avenae)

Cereal cyst nematode (CCN) happens widespread in wheat-producing areas in China nowadays, which makes great threat to wheat production. This paper investigated the effect of fosthiazate treatment on cereal cyst nematode hatching, infection and activity, as well as its toxicity to second instar larvae. Its mode of action on cereal cyst nematode was also preliminary studied. The efficacy of fosthiazate on cereal cyst nematode was studied, combining different application methods and application time. The effect of cereal cyst nematode treatment on wheat yield was also investigated. The main results are listed as follows:1. The results indicated that in pot experiment, agronomic traits of wheat were significantly influenced by H. avenae. When the initial inoculation amount of eggs in per gram soil ranged from5to30, the chlorophyll contents of wheat leaf, dry weight of roots, dry weight of stems, number of spikes, grain numbers, weight of1000kernels and weight of spikes reduced from10.89%to34.46%,30.65%to73.95%,13.93%to58.68%,30.48%to53.33%,3.97%to36.93%,-3.73%to1.28%and-0.72%to35.08%, respectively, compared with the ones which had not been treated with nematode. However, under ideal field conditions, for example abundant water and fertilizer, no significant impact on production indexes of wheat was saw on account of H. avenae. It was indicated that propagation coefficient of H. avenae was negatively correlated with initial egg amount. Overall, the occurrence of H. avenae was potential threat to wheat production. When control measures were proposed, water and fertilizer conditions should be seriously considered, accompanied with the effects on the medium and low-yield field.2. Impregnation method was adopted to test the inhibitory activity of fosthiazate to cereal cyst nematode under laboratory conditions.It was indicated that its toxicity to the second instar larvae was very low, which could not kill the hatched second instar larvae completely even at a high dosage. Thus, the effects of fosthiazate on the hatching, infection and activity cereal cyst nematode were examined. The results showed that in the pre-incubation period (4℃), the hatch of the cysts was not significant affected after fosthiazate treatment. However, in the hatching period (15℃), its hatching was significantly inhibited. The effect of fosthiazate on nematode movement and infestation was clearly observed. We supposed that the inhibition of nematode infection for fosthiazate was achieved mainly because of the inhibition of J2(second instar larvae) movement and the interference on J2location capability (the movement of nematodes to wheat root tissue). Our study showed that the lethal dosage of fosthiazate on cereal cyst nematode second instar larvae was significantly higher than that of inhibiting hatching, movement and infection. Thus, fosthiazate control the nematodes primarily by inhibiting the eggs hatching, reducing its movement and infection.3. The efficacies of fosthiazate with different formulation, application time and application methods on cereal cyst nematode as well as its effect on nematode infection were investigated to establish the control strategies of fosthiazate on cereal cyst nematode. Pot experiment showed that the control efficacies of poison soil method (fosthiazate EC), root-irrigation (fosthiazate EC) and poison soil method (fosthiazate granules) on nematodes were78.08%,60.27%and34.25%, effectively, all of which showed significant inhibition on the nematode amount. In the field trails, the control efficacy of fosthiazate EC root-irrigation on CNN was higher than that of poison soil method (fosthiazate granules), showed effective control on CNN throughout the whole growing season of wheat. Morever, applying fosthiazate EC via irrigation during the turning green stage showed better control efficacy on CNN than treating before winter because the hatching and infection of CCN was at the highlight stage during the turning green stage of wheat.To sum up, applying fosthiazate EC along with irrigation during the turning green stage yields twice the result with half the effort.