About the field management of the middle and later periods of corn in July
It can be regarded as a critical period for the field management of the middle and later periods of corn in July. In this time, the growers should pay attention to topdressing and pests prevention so as to promote the conversion and upgrade of weak seedlings.
a. The main objective of field management is to promote the enlargement of leaves on the middle and upper parts as well as the stocky of stems, thus the ear of corn will increase and become large as well as can prevent the injury and premature senility of leaves. Besides, it can also increase fruit output and fruit weight and achieve high yield.
b.Regarding the dry farming area, the chemical fertilizer should be sprayed in the small holes near the plants in the rainy days, while regarding the irrigated area, broadcast is forbidden to be used. According to the soil nutrient structures, we should scientifically spray micro element fertilizer so as to avoid fertilizer loss and premature senility. In order to prevent fertilizer loss in the later period and ensure that plants can grow strong, foliage dressing can be used combining with pest control measures, in which 0.5-0.7kg urea and 0.2kg monopotassium phosphate will be used, the water consumption will be 50-100kg as well as a certain insecticides will be added, thus it can also prevent ostrinia nubilalis.
c. Farmlands that have high fertility and low density will be easy to have tiller and multi ear phenomenon. Except for some plants that grow very well and can keep 2 fruit cluster in one plant, usually there will be only 1 fruit cluster that can be kept in one plant so as to reduce nutrient consumption. Besides, the ear leaves should not be damaged or removed as well as the excess tillers should also be removed. There are also some of the corns that cannot bear corncob and will form barren stalk due to poor pollination and other factors. These kinds of plants will not only consume water and nutrient, but also will share light and space with plants that can bear corncob. Therefore, we should remove these kinds of plants in time so as to reduce nutrient and water consumption.
d. Regarding Hexi region and Yellow River irrigation area, we should irrigate water ahead of time in the tassel period as well as flowering and filling stage when the drought occurs according to the growth vigor of corns and climate changes, or it will almost have no effect by irrigating too late. Regarding the mid-east dry farming regions where there are some water resources, we can use injection and supplementary irrigation combining with rainwater harvesting water cellar, thus it can promote flowering, pollination and grain filling as well as can reduce drought loss.
e. Focus on preventing ostrinia nubilalis, red spider, armyworm, corn smut, top rot and stem rot. If some of the plants are infected with corn smut, pull out the infected plants in time and deeply bury them outside the field. 3 percent of phoxin granule can be sprayed in the trumpet period with 2-3kg per mu so as to prevent ostrinia nubilalis or it also can use 50 percent of phoxin emulsifiable concentrate and 1000 times liquid 40 percent of chlropyrifos E.C. 2000 times liquid 15 percent of pyridaben or 3000 times liquid 0.9 percent of abamectin insecticide can be used in preventing red spiders; regarding helicoverpa armigera, it can be prevented by using 25 percent of chlropyrifos E.C. according to insect pest situation. Top rot can be prevented by the mist spray of 500 times liquid 50 percent of carbendazol wetabble powder. 800 times liquid 75 percent of chlorothalonil wettable powder or 600 times liquid 50 percent of carbendazim can be sprayed in the early stage of Exserohilum turcicum and Helminthosporium maydis.