first, corn trumpet-shaped mouth medication
the trumpet-shaped mouth period of summer corn, that is, late July or early August, is the peak period of the second generation of corn borer and the key period of prevention and control.
At this time, the total number of corn leaves reaches 11-12, and the upper leaves protrude like a big trumpet, commonly known as the big trumpet stage.
The newly hatched larvae of Ostrinia furnacalis drill into the heart leaves to feed on the young leaves. When the damaged leaves of corn are unfolded, irregular rows of wormholes are formed on the leaves.
if the damage is serious, the leaves are fragmented and can't be unfolded normally, which will easily lead to the abnormal extraction of tassels and affect the normal growth and development of maize.
There are two methods to control corn borer with big trumpet mouthparts by using pesticides:
1. Spraying granular pesticides in the heart leaves to control corn borer.
traditional granular pesticides generally use 2-3g of 5% phoxim granules per mu, which are scattered in the heart leaves of corn.
However, excessive phoxim has the risk of phytotoxicity, and corn borer has strong resistance, so it is more recommended to use Beauveria bassiana mixed with fine soil or slag to poison the larvae.
Beauveria bassiana can continuously and effectively infect parasitic corn borer, control the population, and has a long lasting period, which is environmentally friendly.
2. Spraying pesticides on leaves:
Recommended dosage per mu:
15-2g of 2% chlorantraniliprole suspension or 4ml of 5% chlorfenuron emulsion in water are used in combination with 3g of 1% emamectin benzoate microcapsule suspension or 4g of 12% emamectin benzoate suspension, and the liquid medicine is mainly sprayed on the heart leaves.
This formula has both quick-acting and persistent effects, which can effectively kill corn borer larvae at all ages and eggs. If the control is in place, the persistent period is about 2 days.
It is not recommended to use avermectin products. It is reported that if avermectin is sprayed on corn heart leaves, there is also a risk of phytotoxicity if the dosage is too large.
traditional knapsack sprayer or plant protection drone can be used for pesticide application.
2. Application at booting stage of maize:
At booting stage, the larvae of corn borer are concentrated in the upper part, which harms the unextracted maize tassels. After the tassel of maize was extracted, most of the larvae began to eat into the stalk and stem above the tassel, causing the tassel and upper stem to break.
at this time, you can't use granules for control, but only choose chemical pesticides for spraying. The medication formula can be the same as the big bell mouth period, or other products can be used alternately.
Third, the filling stage of corn
The larvae of corn borer are mainly concentrated in the filaments, and some older insects eat into the axis of the female ear of corn and the nodes of the female ear and its nearby stems, biting the corn seeds, making them broken and moldy.
destroying the stem tissue, affecting nutrient transportation, seriously affecting the development of female ear and grain filling, which is also the most serious period affecting corn yield.
if the prevention and control of corn borer are in place in the first two periods, the occurrence of corn borer will not be very serious in the period of heading and filling. If you miss the prevention and control period, the pests are serious, the corn plants are tall and dense, and the sprayer is no longer suitable, so you can only choose the plant protection drone to fly.
The above are the methods and precautions for controlling corn borer by using pesticides. The specific control time and drug use should be selected according to the insect situation, corn growth process and local drug use history.
The management of maize planting is extensive, and many farmers often pay little attention to the prevention and control of pests and diseases. Don't ignore the harm of corn borer to maize, so as not to cause great losses to maize production.