The Life Cycle Of Cereal Cyst Nematode,Damages To Wheat Yield And Integrated Control

Cereal cyst nematodes (CCN) cause serious damage to cereal crops in the world. Among them, Heterodera avenae is widely distributed in wheat growing areas in16provinces of China and threat the security of wheat production. The damages caused by CCN may have differences in various regions, which probably due to the differences in climate and environment conditions, wheat varieties, farming system and nematode pathotypes. In order to provide the therotical basis for integrated management of CCN, the life cycle and vertical distribution of H. avenae was investigated, the yield losses of different wheat cultivars was evaluated and the different control methods were studied in Peixian, Jiangsu Province.During two growth seasons of winter wheat, from October2010to June2011and October2011to June2012, the life cycle and vertical distribution of H. avenae on wheat was investigated systematically. The result showed that Peixian population finished only one life cycle during the whole growth season. Before wheat over-wintering, a few second stage juveniles (J2) of H. avenae were hatched, however only few of them infected the root systems and none of them developed in normal. During the re-greening period, the hatching peak of J2appeared in soil and infected into roots massively. In tassel period, the white females appeared on roots which can be seen by naked eyes and some males can be observed from roots and soil. During maturation period of wheat, the white females changed into brown cysts and fell into soil for over-summering. The results for vertical distribution revealed that cysts mainly concentrated in soil layer under0-10cm. The hatched J2also aggregated in the same layer and the peaks appeared in re-greening period, which coincided with the life cycle of CCN in field.The yield losses caused by Peixian population of H. avenae on seven wheat cultivars were evaluated in field conditions by using5%aldicarb granular nematicide as a chemical control. The results showed that H. avenae reproduced well on all tested cultivars, but the reproduction factor (Rf) on Huaimai20was the least, which lower than1.0. At the harvest period, all wheat cultivars have no significant differences in plant height, spike length, grain number per spike and thousand-grain weight when compared with nematicide controls revealed by t-test at level of a=0.05. However, the cultivars showed the significant differences in spike number per square meter when compared with that of the control, which may caused the differences in wheat yield. The wheat cultivars tested in the study demonstrated the different CCN resistance. The yield losses rate of Huaimai20and Yanfu188was greater than that of other cultivars, with12.8%and12.4%, respectively.The integrated control of H. avenae on wheat was studied under field conditions. The experiment included chemical seed-coatings No.1,2and3, abamectin seed-coating,0.5%abamectin granule, biocontrol product of Bacillus subtilis, and agricultural measure by fertilizer supplement and compacting after sowing. Eight treatments were designed and the field plots were arranged by contrast design method. The results showed that chemical treatments have effects on inhibiting the reproduction of nematodes and increasing the wheat yield, in which avermectin seed coating1:30was the best. The treatment with supplement complex fertilizer combined with compacting after sowing has no effect on nematode reproduction, but can increase the wheat production slightly. Biocontrol Bacillus subtilis neither inhibited nematode growth nor increased the wheat production. The integrated control strategy is critical for effective management of cereal cyst nematode on wheat.