為什么要裝防蟲(chóng)網(wǎng)？
1、能有效防蟲(chóng)。覆蓋防蟲(chóng)網(wǎng)后，基本上可免除菜青蟲(chóng)、小菜蛾、蚜蟲(chóng)等多種蟲(chóng)害。農(nóng)產(chǎn)品覆蓋防蟲(chóng)網(wǎng)后可以有效的免除菜青蟲(chóng)、小菜蛾、甘藍(lán)夜蛾、斜紋夜蛾、黃曲跳甲、猿葉蟲(chóng)、蚜蟲(chóng)等多種害蟲(chóng)的為害。據(jù)試驗(yàn)，防蟲(chóng)網(wǎng)對(duì)白菜菜青蟲(chóng)、小菜蛾、豇豆莢螟、美洲斑潛蠅防效為94-97%，對(duì)蚜蟲(chóng)防效為90%。
2、可以防病。病毒傳播會(huì)給溫室大棚種植帶來(lái)災(zāi)難性的后果，特別是蚜蟲(chóng)傳毒。但溫室大棚安裝防蟲(chóng)網(wǎng)后就切斷了害蟲(chóng)傳毒途徑，大大減輕了病毒病的發(fā)病率，防效為80%左右。
3、調(diào)節(jié)氣溫、土溫和濕度。在炎熱的季節(jié)，用白色防蟲(chóng)網(wǎng)覆蓋溫室大棚，試驗(yàn)表明：炎熱的7-8月，在25目白色防蟲(chóng)網(wǎng)中，早晨和傍晚的氣溫與露地持平，而晴天中午比露地低1℃左右。早春3-4月，防蟲(chóng)網(wǎng)覆蓋棚內(nèi)比露地氣溫高1-2℃，5厘米地溫比露地高0.5-1℃，能有效地防止霜凍。此外防蟲(chóng)網(wǎng)可阻擋部分雨水落入棚內(nèi)，降低田間濕度，減少發(fā)病，晴天能降低大棚內(nèi)的水分蒸發(fā)量。
4、有遮光效果。夏季光照強(qiáng)度大，強(qiáng)光會(huì)抑制蔬菜營(yíng)養(yǎng)生長(zhǎng)，特別是葉菜類(lèi)蔬菜，而防蟲(chóng)網(wǎng)可起到一定的遮光作用，20-22目銀灰色防蟲(chóng)網(wǎng)一般遮光率在20－25%。
防蟲(chóng)網(wǎng)形似窗紗，具有抗拉強(qiáng)度大，抗紫外線、抗熱、耐水、耐腐蝕、耐老化等性能，無(wú)毒無(wú)味，使用壽命一般為4-6年，最高可達(dá)10年。它既有遮陽(yáng)網(wǎng)的優(yōu)點(diǎn)，又克服了遮陽(yáng)網(wǎng)的不足之處，因而值得大力推廣，那么問(wèn)題來(lái)了：我們應(yīng)該選用什么樣的防蟲(chóng)網(wǎng)？
型號(hào)選擇
秋季很多害蟲(chóng)開(kāi)始向棚內(nèi)轉(zhuǎn)移，尤其是一些蛾類(lèi)及蝶類(lèi)害蟲(chóng)，由于這些害蟲(chóng)的體形較大，菜農(nóng)可以使用目數(shù)相對(duì)較少的防蟲(chóng)網(wǎng)，如30-60目的防蟲(chóng)網(wǎng)。但是對(duì)于棚外雜草較多，粉虱較多的，要根據(jù)粉虱的較小體型，防止其從防蟲(chóng)網(wǎng)的孔眼中進(jìn)入，建議菜農(nóng)使用較密的防蟲(chóng)網(wǎng)，如40-60目的。
顏色選擇
例如，薊馬對(duì)藍(lán)色有很強(qiáng)的趨性，使用藍(lán)色防蟲(chóng)網(wǎng)容易將棚外的薊馬吸引到大棚周?chē)?，一旦防蟲(chóng)網(wǎng)覆蓋不嚴(yán)就會(huì)使大量的薊馬進(jìn)入棚中造成危害；而使用白色防蟲(chóng)網(wǎng)，大棚內(nèi)就不會(huì)發(fā)生這種現(xiàn)象，而與遮陽(yáng)網(wǎng)配合使用時(shí)，以選擇白色為宜。還一種銀灰色防蟲(chóng)網(wǎng)對(duì)蚜蟲(chóng)有較好的拒避作用，黑色防蟲(chóng)網(wǎng)遮陰效果顯著，冬季、連陰天不適宜使用。
一般春秋季節(jié)和夏季相比，溫度較低，光照較弱，宜選用白色防蟲(chóng)網(wǎng)；夏季為了兼顧遮陽(yáng)、降溫，宜選用黑色或銀灰色防蟲(chóng)網(wǎng)；在蚜蟲(chóng)和病毒病發(fā)生嚴(yán)重的地區(qū)，為了驅(qū)避蚜蟲(chóng)、預(yù)防病毒病，宜選用銀灰色防蟲(chóng)網(wǎng)。
注意事項(xiàng)
1、在播種或定植前采用高溫悶棚或噴施低毒農(nóng)藥殺滅土壤中的寄生蟲(chóng)蛹、幼蟲(chóng)。
2、栽植時(shí)秧苗最好帶藥入棚，并挑選無(wú)病蟲(chóng)害的健壯植株。
3、加強(qiáng)日常管理，進(jìn)出溫室大棚要將棚門(mén)關(guān)嚴(yán)，在進(jìn)行農(nóng)事操作前要對(duì)有關(guān)器
物進(jìn)行消毒，防止病毒傳入，以確保防蟲(chóng)網(wǎng)的使用效果。
4、要經(jīng)常檢查防蟲(chóng)網(wǎng)有無(wú)撕裂口，一旦發(fā)現(xiàn)應(yīng)及時(shí)修補(bǔ)，確保溫室大棚內(nèi)無(wú)害蟲(chóng)侵入。
5、確保覆蓋質(zhì)量。防蟲(chóng)網(wǎng)要全封閉覆蓋，四周用土壓嚴(yán)實(shí)，并用壓膜線固定牢固；進(jìn)出大、中棚和溫室的門(mén)，必須安裝防蟲(chóng)網(wǎng)，并注意進(jìn)出時(shí)隨即關(guān)好。小拱棚防蟲(chóng)網(wǎng)覆蓋栽培，棚架高度要明顯高于作物，避免菜葉緊貼防蟲(chóng)網(wǎng)，以防害蟲(chóng)由網(wǎng)外采食或產(chǎn)卵于菜葉。用于放風(fēng)口封閉的防蟲(chóng)網(wǎng)，與透明覆蓋物間不能留有縫隙，以免給害蟲(chóng)留出進(jìn)出通道。
6、綜合配套措施。除防蟲(chóng)網(wǎng)覆蓋外，再結(jié)合抗病蟲(chóng)良種、耐熱良種、無(wú)公害套餐肥料、生物農(nóng)藥、無(wú)污染水源、微噴微灌等綜合配套措施，就可以獲得更佳的效果。
7、妥善使用、保管。防蟲(chóng)網(wǎng)田間使用結(jié)束后，應(yīng)及時(shí)收下，洗凈、吹干、卷好，以延長(zhǎng)使用壽命，增加經(jīng)濟(jì)效益。
Why install insect net?
1.It can effectively prevent insects.After covered with the net,the pests such as Pieris rapae,Plutella xylostella and aphids can be avoided.Agricultural products covered with insect proof net can effectively avoid the damage of Pieris rapae,Plutella xylostella,cabbage armyworm,Spodoptera litura,scarab beetle,leaf beetle,aphid and other pests.According to the test,the control effect of the net on cabbage caterpillar,Plutella xylostella,cowpea pod borer and Liriomyza sativae was 94-97%and 90%against aphids.
2.It can prevent disease.Virus transmission will bring disastrous consequences to greenhouse planting,especially aphid transmission.However,the installation of insect proof nets in greenhouse can cut off the transmission route of pests,greatly reducing the incidence rate of viral diseases,and the control effect is about 80%.
3.Adjust air temperature,soil temperature and humidity.In the hot season,the greenhouse was covered with white insect proof net.The test showed that the temperature in the morning and evening was the same as that in the open field in the 25 mesh white insect proof net from July to August in the hot season,but it was about 1℃lower at noon than that in the open field on a sunny day.From March to April in early spring,the air temperature in the shed covered with insect proof net was 1-2℃higher than that in open field,and the ground temperature of 5cm was 0.5-1℃higher than that in open field,which could effectively prevent frost.In addition,the insect net can prevent some rainwater from falling into the shed,reduce the field humidity,reduce the incidence of disease,and reduce the water evaporation in the greenhouse on sunny days.
4.It has shading effect.The light intensity is high in summer,and the strong light will inhibit the vegetative growth of vegetables,especially leafy vegetables.The insect proof net can play a certain role in shading.The shading rate of 20-22 mesh silver gray insect proof net is 20-25%.
The insect proof net is shaped like a window screen.It has high tensile strength,ultraviolet resistance,heat resistance,water resistance,corrosion resistance and aging resistance.It is non-toxic and tasteless.Its service life is generally 4-6 years,up to 10 years.It not only has the advantages of the sunshade net,but also overcomes the shortcomings of the sunshade net,so it is worth promoting.So the question comes:what kind of insect proof net should we choose?
Model selection
In autumn,many pests begin to move to the shed,especially some moths and butterflies.Due to the large size of these pests,vegetable farmers can use relatively small mesh nets,such as 30-60 mesh nets.However,if there are more weeds and whiteflies outside the shed,the smaller size of whiteflies should be taken to prevent them from entering through the holes of the nets.It is suggested that vegetable farmers should use dense nets,such as 40-60 mesh.
Color selection
For example,thrips have a strong tendency to blue,the use of blue insect net will easily attract thrips outside the shed to the surrounding of the greenhouse,once the insect net is not covered tightly,a large number of thrips will enter the shed and cause harm;while using white insect net,this phenomenon will not occur in the greenhouse,and when used with sunshade net,white should be selected.In addition,a silver grey insect net has a good repellent effect on aphids.The black net has a significant shading effect,and is not suitable for use in winter or even cloudy days.
Generally,in spring and autumn,compared with summer,the temperature is lower and the light is weaker,so the white insect prevention net should be selected;in summer,in order to take into account the shading and cooling,the black or silver gray insect prevention net should be selected;in the areas where aphids and virus diseases occur seriously,silver grey insect prevention net should be used in order to drive away aphids and prevent virus diseases.
matters needing attention
1.Before sowing or planting,the pupae and larvae of parasites in the soil were killed by high-temperature airtight shed or spraying low-toxic pesticides.
2.When planting seedlings,it is best to bring medicine into the shed,and select healthy plants without diseases and insect pests.
3.Strengthen the daily management,close the door of the greenhouse when entering and leaving the greenhouse,and check the relevant equipment before agricultural operation
In order to ensure the use effect of the anti insect net,disinfection is carried out to prevent the introduction of virus.
4.It is necessary to regularly check whether there is tearing crack in the insect proof net.Once found,it should be repaired in time to ensure that there is no insect invasion in the greenhouse.
5.Ensure coverage quality.The insect proof net should be completely closed and covered,the soil should be pressed tightly around,and the film pressing line should be used to fix it firmly;the doors of large and medium-sized sheds and greenhouses must be installed with insect proof nets,and attention should be paid to close them when entering and leaving.The height of the trellis should be significantly higher than that of the crops in the small arched shed,so as to prevent the pests from eating or laying eggs on the leaves of the plants.There should be no gap between the insect proof net used for sealing the vent and the transparent cover,so as to avoid leaving passage for the pest.
6.Comprehensive supporting measures.In addition to the coverage of insect prevention net,combined with the comprehensive supporting measures such as disease resistant and insect resistant varieties,heat-resistant varieties,pollution-free fertilizer,biological pesticides,pollution-free water source,micro spray and micro irrigation and other comprehensive supporting measures can achieve better results.
7.Proper use and storage.After the use of the net in the field,it should be collected in time,cleaned,dried and rolled up in order to prolong its service life and increase its economic benefits.
