Jidi Wang,Maode Xing,Jun Geng,Chao Liu,Ping Liu

Zibo Academy of Agricultural Sciences/Zibo Branch of Shandong Academy of Agricultural Sciences,Zibo 255033,China

Abstract In order to better serve cotton farmers,green prevention and control technologies of pests are formulated according to the sowing,seedling and adult stages of cotton from the aspects of ecological prevention and control,physical prevention and control,biological control and scientific use of pesticides,thus realizing green prevention and control of pests during the whole growth period of cotton.

Keywords Shandong Province;Cotton field;Pest;Green prevention and control

Shandong Province,located in the lower reaches of the Yellow River,is the world main area suitable for growing cotton,and cotton plantation area now ranks third in China.The cotton innovation team of Shandong Agricultural Industry Research System was established in 2012.After seven years of introducing new technologies and scientific research,the cotton pest prevention and control technology has been transformed from integrated prevention and control to green prevention and control.Cotton production is transformed from pursuing high yield cultivation of cotton to green,high quality and efficient development of cotton field.

Pests refer to all organisms that harm plants,mainly including diseases,pests and weeds.Green prevention and control at abroad refers to biological control.Greathead described green prevention control as"a means to control another pest by introducing,reproducing and releasing predatory and parasitic natural enemies or pathogenic bacteria".BeDach extended the definition of green prevention and control,stating that"green prevention and control refers to the use of predatory and parasitic natural enemies or pathogenic bacteria to keep the population density of another pest at a low level".In China,the Ministry of Agriculture(MOA)issued Opinions on Promoting Green Prevention and Control of Crop Diseases and Pests in 2011,and pointed out that"green prevention and control of crop diseases and pests refers to plant protection measures to control the harm of crop diseases and pests by adopting environment-friendly measures such as ecological regulation,biological control,physical control and scientific medication".Currently,green prevention and control of crop diseases and insects has become an important part of green production of crops in China,and is the main measure to reduce the amount and increase the efficiency of pesticides in farmlands[1].

Pests in cotton field refer to all organisms that harm cotton during the whole growth period,mainly including cotton diseases,pests and weeds in cotton fields.

Diseases in cotton field mainly include cotton Fusarium wilt,cotton Verticillium wilt,cotton diseases at seedling stage and cotton boll diseases.Pests in cotton field mainly include Aphis gossypii,Tetranychus cinnabarinus,Thrips tabaci,Helicoverpa armigera,Lygus lucorum and Bemisia tabaci.Weeds in cotton field mainly include more than a dozen annual or perennial weeds such as Eleusine indica,Acalypha australis,Digitaria sanguinalis,Cyperus rotundus,Phragmites australis,Portulaca oleracea,Eclipta prostrate,Imperata cylindrical,etc.[2-4].

1 Sowing Stage

1.1 Major control objects The major weeds are annual or perennial weeds in cotton field.The major diseases are cotton Fusarium wilt,cotton Verticillium wilt,cotton diseases at seedling stage(mainly damping-off,followed by red rot,anthracnose,etc.).The major pests are A.gossypii,T.cinnabarinus,etc.

1.2 Control measures

1.2.1 Weeds in cotton field.In the spring sowing cotton planting area,the sowing density of cotton increases due to the implementation of light and simplified cultivation[5-7],and there are more cotton stubbles in cotton fields.Therefore,deep ploughing should be carried out after cotton harvest,with the depth of 30-35 cm.Rotary tillage must be performed twice,with the depth of 10 cm.If the previous crop is garlic or wheat,deep ploughing should be carried out after harvest,and the depth should be 20-25 cm.Rotary tillage must be performed twice,with the depth of 10 cm.

The strategy of"combination of sealing and supplementing"is adopted for weed control.Before sowing,if there are perennial weeds,such as Convolvulus arvensis,Galium aparine,etc.,fluroxypyr+glyphosate should be selected to control the weeds.For the control of sedge weeds,6-8 g of 75% halosulfuron-methyl WDG can be used for soil spray[8-9].

In mid-April,combined with raking cotton fields,480 g/L trifluralin EC(dose 2.7 L/hm2)or 330 g/L pendimethalin EC(dose 2.25 L/hm2)was mixed with soil before cotton sowing[10-11].

1.2.2 Selection of variety.Cotton varieties with insect and disease resistance,high yield and high quality are selected,and the seed quality should be in line with the relevant national standards.High quality cotton varieties with good prematurity,easy management and concentrated boll setting and boll opening can be selected for spring sowing in north Shandong cotton-growing region,such as Lumian 1131,Lumian 696,Lumian 338 and K836.In the southwest cotton-growing region of Shandong Province where yields two crops a year such as cotton/garlic,and cotton/wheat,high yield and high quality hybrid cotton varieties,such as Lumianyan 24 and Lu H424,or conventional cotton varieties with strong production capacity per plant should be selected.High-quality,early-maturing,short-season cotton varieties,such as Lumian 532 and Lumian 241,should be selected for post-garlic(wheat)direct sowing,to control cotton Fusarium wilt,cotton Verticillium wilt,H.armigera,etc.

1.2.3 Seed treatment.25% Thiamethoxam·fludioxonil·metalaxyl-M FS at the dose of 300 g/100 kg seeds,8% dinotefuran at the dose of(1 450-2 500)g/100 kg seeds or 600 g/L imidacloprid FS(300-400 mL/100 kg seeds)+2% tebuconazole ZF(133.5-200.0 g/100 kg seeds)can be used for seed coating.15% Thifluzamide·dinotefuran ZF at the dose of(3 300-5 000)g/100 kg can be used for seed dressing.If possible,3 kg of 2% imidacloprid GR can be applied with sowing on the basis of seed coating,to control A.gossypii,T.cinnabarinus,and other diseases and insect pests at cotton seedling stage.

1.2.4 Crop rotation or intercropping.Conditional plots can be rotated with wheat,corn,pepper,black wheat,etc.,or intercropped with watermelon,mung beans,red beans,which can effectively reduce continuous cropping obstacles of cotton and reduce the occurrence of cotton diseases and insect pests[12].

2 Seedlings Stage

2.1 Major control objects The major pests are A.gossypii,T.cinnabarinus and T.tabaci.The major weeds are perennial weeds,such as sedge weeds,C.arvensis,etc.

2.2 Main control measures

2.2.1 Ecological prevention and control.(i)Sowing in proper time.In spring sowing area,seeds are generally sown from April 20 to April 30,and the latest sowing is before May 5.In garlic-cotton intercropping area,seedlings are generally raised in early April and transplanted in the field from May 15 to May 20.Wheat sowing(direct sowing after garlic)is generally conducted from the end of May to June 5.

(ii)Seedling releasing and final singling in time.When the first true leaf of cotton seedling unfolds,seedlings are planted in time,and the planting distance of cotton seedlings must be as uniform as possible.

(iii)Rational close planting.Light and simplified cultivation of cotton is the main planting mode of cotton in Shandong Province[12].In plots with good fertility and water conditions,cotton varieties are densely planted,generally (6-6.75)×104plants/hm2.In plots with poor fertility and water conditions,the planting density is generally (6.75-7.5)×104plants/hm2.In post-wheat (garlic)direct sowing fields,the planting density is generally(8.25-9)×104plants/hm2.

(iv)Irrigation and fertilization.Before cotton sowing,the places with water conditions should be irrigated in advance,and cotton seeds must be sowing immediately after rainfall in the areas without water conditions.Commercial organic fertilizer(organic matter content≥30%)can be sprayed at the dose of 1 500 kg/hm2,or high-quality farmyard manure 3 t+diammonium phosphate 450 kg,controlled release urea 225 kg,and potassium sulfate 150 kg can be applied per hm2.Drainage ditch must be left in advance in waterlogged lowland.

2.2.2 Chemical control.When A.gossypii,T.cinnabarinus and T.tabaci have reached the control indexes,15% bifenthrin·dinotefuran OD at the dose of 600 mL/hm2and 50% pymetrozine·dinotefuran WDG at the dose of 300 g/hm2can be sprayed on leaves to control A.gossypii,as well as T.cinnabarinus and T.tabaci.In cotton-growing fields with severe incidence of red spider,foliar sprays can be performed using 10% abamectin SC 7 000-10 000 times dilution.

For inter-row weeds,108 g/L haloxyfop-R-methyl at the dose of 375-450 mL/hm2can be sprayed on stem and leaves before three-leaf stage to control annual weeds.For perennial weeds,30% glyphosate·isopropylammonium AS at the dose of 2 745-5 490 mL/hm2can be used for interrow directional spray[11].

3 Adult Stage

3.1 Major control objects The major pests are A.gossypii,L.lucorum,Helicoverpa armigera,B.tabaci and T.tabaci.The major diseases are cotton Fusarium wilt,cotton Verticillium wilt,cotton boll diseases(cotton blight,red rot,pink rot).

3.2 Control measures

3.2.1 Ecological prevention and control.(i)Setting trap belt to trap and kill pests.A 1-2 m mung bean trap belt is planted around the cotton field,and foliar spray of 1% celangulin EW at the dose of 450-600 mL/hm2is regularly performed to trap and kill Mirid pests[13].

(ii)Fighting against drought and drainage.In case of drought years,irrigation and watering should be timely conducted.In case of waterlogging,drainage must be timely conducted to keep the cotton fields free of water.

(iii)Chemical control in proper time.The core of light and simplified cultivation of cotton is selecting varieties resistant to cotton boll diseases,late sowing and increasing planting density,so as to realize the purpose of no branch-cutting.The main guarantee measure is timely chemical control of cotton,especially summer sowing cotton.The specific measures are described in 3.5.

(iv)Intercropping weeding.Intertillage is timely carried out in cotton bud period.The purpose of intertillage is to cut off the capillary in the soil,reduce soil moisture evaporation and artificial control of weeds between cotton rows.

3.2.2 Physical trapping and control.(i)Insecticidal lamp.From late May to September 30,a set of frequency vibrating solar insecticidal lamp should be installed every 1-2 hm2.In the initial incidence period of adults,trap bags should be cleaned once every 7-14 d,and during the peak occurrence period of adults,trap bags should be cleaned once every 1-7 d[14].

(ii)Insect sex pheromones.In mid May,the sex pheromone box of L.lucorum is installed,and the height of lure core is always controlled at 0-15 cm over the top of cotton plants;1-3 cm of water is kept in the trap box,and 1%-2% fruit and vegetable detergent is added to the water.The water in the trap box is changed once every 15 d.Two boxes are installed every 1 hm2,and the cores are changed once a month.The boxes are installed from mid June to September 30,to control L.lucorum in cotton fields[15-16].

3.2.3 Biological control.In the early incidence period of aphids, Harmonia axyridis cards are released at the density of 1 500 cards/hm2,and each card has 20 eggs.The cards are hanging under the upper leaf surface of plants.The cards are released once every 15 d for consecutive two times,to control A.gossypii[17-18],as well as B.tabaci in cotton fields[19].

3.2.4 Chemical control.(i)Early budding stage.4.5% Beta-cypermethrin EC 600 mL/hm2+10% imidacloprid WP 450 g/hm2+250 g/L mepiquat AS 75 g/hm2+Tianda 2116 are sprayed on leaves,to control A.gossypii,as well as T.cinnabarinus and T.tabaci,and regulate the growth of cotton[20].

(ii)Budding stage.4.5%Beta-cypermethrin EC 600 mL/hm2+5% acetamiprid EC 195 mL/hm2+250 g/L mepiquat AS 150 g/hm2+K2HPO4are sprayed on leaves,to control A.gossypii,as well as T.cinnabarinus and T.tabaci,and regulate the growth of cotton.

(iii)Initial flowering stage.200 g/L Chlorantraniliprole SC150 mL/hm2+5% acetamiprid EC 195 mL/hm2+250 g/L mepiquat AS 180 g/hm2+NPK water-soluble fertilizer(14-14-30)500 times dilution are sprayed to control A.gossypii,H.armigera,as well as T.tabaci and B.tabaci,and regulate the growth of cotton[21].

(iv)Full-blossom stage.50% Sulfoxaflor WDG 180 g/hm2+5% acetamiprid EC 195 mL/hm2+250 g/L pyraclostrobin EC 450 mL/hm2+250 g/L mepiquat AS 210 g/hm2+NPK water-soluble fertilizer(14-14-30)500 times dilution are sprayed to control A.gossypii,H.armigera,L.lucorum,as well as T.tabaci and B.tabaci.The agents would also prevent and control diseases at boll stage,such as cotton Fusarium wilt,cotton Verticillium wilt,and regulate the growth of cotton[22].

(v)Early open-boll stage.50% Sulfoxaflor WDG 180 g/hm2+50% azoxystrobin WDG 750 g/hm2+250g/L mepiquat AS 240 g/hm2+NPK water-soluble fertilizer(14-14-30)500 times dilution are sprayed to control H.armigera,L.lucorum,boll diseases,as well as T.tabaci and B.tabaci,and regulate the growth of cotton.

(vi)Open-boll stage.When the boll opening rate is 60%-70%,40%Ethrel 3 L/hm2,60% thidiazuron WP 0.6 L/hm2and methyl oleate(adjuvant)are evenly sprayed on cotton plants once every 7 d for consecutive two times.The application will promote the early mature of cotton,and realize concentrated defoliation and boll opening,which will benefit cotton pickup.

The amount of mepiquat AS can be increased according to cotton growth,soil fertility, precipitation frequency and amount of precipitation.

3.3 Choosing advanced machinery,implementing unified prevention and control It is recommended to use high bar sprayer for foliar sprayer before closing of crop,and plant protection UAV is recommended for foliar spraying after closing of crop[23-24].

The following points should be noted when selecting plant protection UAV spray[25].

(i)For field operations,calm,light air,Light breeze or at least gentle breeze is required,and the flying altitude is generally 1.7-2.7 m over the top of cotton plants.

(ii)Field operation shall be carried out before 10:00 am or after 17:00 pm in sunny days or after rainfall.

(iii)The dosage forms such as aqueous solution and emulsifiable concentrate are appropriate,while suspension concentrate and powder are forbidden.

(iv)When mixed with micro fertilizer and biological fertilizer,pre-test should be done in advance,and the phenomena of turbidity and precipitation are strictly prohibited.

(v)Clean neutral or slightly acidic tap water can be selected as dilute water,and pure water can be used if possible.

(vi)Special adjuvants for plant protection UAV should be selected,and their dosages follow the requirements of adjuvants.

(vii)Deficient spraying or respraying is strictly prohibited.

(viii)Used pesticide bottles or pesticide bags should be cleaned,stored and processed concentratedly.

(ix)During the whole operation process,site operators wear protective equipment such as overalls,special protective gloves and masks.