The Study On The Key Control Points And Control Methods Of Wheat And Corn Pests In Hebei Province

Wheat and corn are important food crops.The wheat-maize planting pattern of two seasons a year is the main planting pattern in the central and southern regions of Hebei Province.In the whole growth process of wheat and maize,a variety of diseases andpests would occur in each growth period.Farmers’ profits from growing wheat and corn are very low.In order to save production cost and consider ecological benefits,it is necessary to reduce the cost of pest control and pesticide investment,generally,the pest control of wheat or maize should not be more than 2 times.We need to make clear the main contradictions that affecting the yield and quality of wheat and maize and develop simple and effective methods to solve these problems,so as to ensure the sustainable development of agriculture.In this paper,based on the investigation of the species,quantity and damage degree of pests in different growth stages of wheat and maize,the key species and suitable period of pest control will are identified.At the same time,the prevention and control of key diseases should be taken into account.It needs to find out the key control points in the whole production process and to formulate the integrated pest control technology system suitable for the current production system.The main results are as follows.1.Through the investigation of pest species,occurrence period and damage degree and the key wheat pest species in wheat field were identified.The key pests in winter wheat field were wheat aphids and Sitodiplosis mosellana(Géhin)which were dominant in wheat field.The occurrence peak of wheat aphid occurred at the filling stage of wheat.The proportion of wheat aphids was 96.60%of the total number of pests in the wheat field of Baoding Agricultural Research Institute.The proportion of wheat aphids was 99.00%of the total number of pests in Kantai garden of Hejian City,and the proportion of other pests was only 1.00%.However,S.mosellana only occured in a few plots,and its larvae fed directly on wheat grains,which was the most important pest to yield.2.By investigating the species,occurrence period and damage degree and the key corn pests in corn field were identified.The results showed that the number of Rhopalosiphum maidis(Fitch)in summer corn field was the largest,and its peak was from milk stage to wax stage.The proportion of R.maidis was 98.22%and 49.42%of the total number of pests surveyed in Baoding Agricultural Research Institute and in Kantai garden farm of Hejian City,respectively.The overall number of corn ear pests(Helicoverpa armigera Hübner,Ostrinia furnacalis Guenee and Conogethes punctiferalis Guenee)was not large.The proportion of corn ear pests was 0.11%of the total number of surveyed pests in Baoding Agricultural Research Institute.The proportion of corn ear pests accounted for 17.30%in summer corn field in Kantai garden farm of Hejian ity.However,the investigation results of corn ear pests in many fields showed that the average pestear rate in summer maize was 81.0%.Among corn ear pests,The population numbers of H.armigera and O.furnacalis were more than C.punctiferalis.Because corn ear pests fed the corn seeds directly,creating wounds would result in the occurrence of corn ear rot diseases.Therefore,The harm of corn ear pests were more serious,and they were the key pests in corn field.3.The key control period and control method of wheat key pests.The number of wheat aphids and natural enemies in the spraying area decreased 11 days after spraying thiamethoxam,Lambda-cyhalothrin and chlorpyrifos at 50%heading;there was no significant difference in the number of wheat aphids between the control area and the spraying area 24 days after spraying,but the number of natural enemies in the control area was significantly higher than that in the spraying area.Therefore,the control effectiveness of clothianidin on wheat aphids was the lowest,it had little effect on natural enemies.The number of wheat aphids decreased at 13 days after spraying clothianidin and Lambda-cyhalothrin at 7 days after wheat flowering.There was no difference in the number of aphids among the three treatments.However,the effect of spraying on natural enemies was too great,so spraying at this time was not recommended.The control effectiveness of Lambda-cyhalothrin on S.mosellana was 97.6%when spraying twice at 17%heading rate and at 70%heading rate,and 90.0%when spraying once at 17%heading rate.There was no significant difference between them.However,the control effectivenessjust only was 64.4%when spraying once at 70%heading rate.Considering many factors in actual production,the key control point of wheat aphid and S.mosellana was that the heading rate of wheat was 17%～50%.4.Study on the key period and method of corn key pest control.In order to determine the best time to release Trichogramma,the occurrence dynamics of adult of corn ear pests in maize were systematically investigated.The species of ear pests and the overlapping period of three kinds of adults were determined,and the suitable species,application time and times of Trichogramma were determined to achieve the best control effectiveness.The results showed that the corn big bell mouth stage(overlapping period of the second generation of H.armigera adults and the first generation of O.furnacalisa dults)and the silking stage(overlapping period of the third generation of H.armigera adults,the second generation of O.furnacalis adults and the second generation of C.punctiferalis adults)were the key periods of releasing Trichogramma.In 2019 and 2020,Trichogramma was released three times in 10hm2 summer corn field of Kantai garden farm in Hejian to control corn ear pests.In 2019,the pest ear rate in Trichogramma releasing area was 45%,while in 2020 that was 94%.The effect of releasing Trichogramma was not obvious.5.Key control points and control methods of diseases and insect pests in wheat-maize cultivation mode of two seasons a year.The key control points of wheat pests were at sowing and heading stages.And the prevention and control method was seed treatment and spraying insecticides and fungicides once when 17%～50%wheat heading rate which mainly controled S.mosellana,wheat aphid and wheat head scab,as well as other diseases and insect pests.The key control points of corn pests were in the sowing period and bell mouth stage.The control method was seed treatment(seed dressing),which could effectively prevent underground pests,R.maidis,Laodelohax striatellus and other pests.In the bell mouth stage,Trichogramma was released,or insecticide was sprayed to control H.armigera and O.furnacalis.Adding fungicides could also prevent corn rust,brown spot and other diseases.