Symptoms and Control methods of the latest Maize rough Dwarf Disease

Maize rough dwarf virus is a kind of maize virus disease caused by maize rough dwarf virus. Maize rough dwarf virus belongs to plant reovirus group. It is a double-stranded RNA spherical virus with double capsid. It is transmitted by gray planthopper in a persistent way. Maize rough dwarf disease is an important disease prevalent in corn production areas in northern China. Let's take a look at the symptoms and control methods of corn rough dwarf disease.

Harmful symptoms of Maize rough Dwarf Disease

The maize rough dwarf virus is spherical and can survive for 37 days at a passivation temperature of 800C and 20 ℃. The virus is transmitted by insects, mainly gray planthopper, which belongs to persistent transmission. The incubation period is 15 won for 20 days. It can also infect wheat (causing blue dwarf disease), oats, millet, sorghum, barnyardgrass and so on.

The main results are as follows: 1. Symptoms: maize can be infected during the whole growth period, especially in the seedling stage, and 5 to 6 leaves can show the disease. transparent oil-immersed chlorotic virtual lines begin to appear at the base of the heart leaf and on both sides of the midvein, and gradually spread to the whole leaf. The diseased seedlings are thick green, the leaves are stiff, wide, short and thick, the heart leaves can not expand normally, the growth of the diseased plants is slow, and waxy white raised stripes are produced on the veins on the back of the dwarfing leaves, the leaves of the plants with obvious rough feeling are wide, short and stiff, the leaf color is dark green, and the internodes are thick and short. The top leaf is clustered like a gentleman's orchid. The veins of leaf back, leaf sheath and bract have waxy white protuberances of different thickness and have obvious roughness. At the stage of 9 to 10 leaves, the dwarfing phenomenon of the diseased plant was more obvious, the upper Internode was shortened and swollen, the top leaves were clustered, the height of the diseased plant was less than half of the healthy plant, and most of the diseased plants could not heading and fruiting. Although a few male ears could be produced, they had few branches and no pollen. The fruit ear is deformed, the filament is very few, the plant is seriously dwarfed, the male ear is degenerated, the female ear is deformed, and can not bear fruit seriously.

2. Harm: since 1993, the occurrence of maize rough dwarf disease has increased obviously, which has caused great losses to the corn production in our city. When it occurred in 1996, the rate of diseased plants in general diseased fields reached 40%, and the average yield was reduced by 10% to 30%. It occurred in Huang-Huai region for three consecutive years from 2007 to 2009. How to control maize virus disease, especially the harm of maize rough dwarf disease (MRDV), has become a problem of great practical significance. Therefore, we have conducted a systematic investigation on maize rough dwarf disease in recent years. It was found that 85.16% of the diseased maize plants basically lost or lost yield, and the plant height was only 1 / 2 of that of the healthy plant, and there was no female ear or no female ear. 98.44% of the plants had a grain weight loss rate of more than 50%.

3. Characteristics: rough dwarf virus overwinters in winter wheat and other weeds in northern China. It can also overwinter in poisonous insects. After corn was unearthed the following year, the virus was transmitted to corn seedlings or sorghum, millet and weeds by virus-transmitting insects. Maize is susceptible to disease before the 5-leaf stage, and the resistance is enhanced after the 10-leaf stage, even if infected. If the ten stages of maize seedling emergence meets with the migration peak of virus-transmitting insects, the disease is serious, so the sowing time of corn is closely related to the severity of the disease. for example, the corn sown in the middle of May in Hebei Province is in the first generation at the seedling stage and the adult stage of gray planthopper is in full bloom. Extensive field management, many weeds, many gray planthoppers, serious disease.

Control methods of Maize rough Dwarf Disease

1. Agricultural prevention and control methods

In the prevention and control of maize rough dwarf disease, we should adhere to the comprehensive control policy of agricultural control, supplemented by chemical control, and its core is to control the source of poison, reduce the source of insects and avoid harm.

① strengthened monitoring and forecasting: focus on locating and regularly investigating the plant rate and severity of rough dwarf disease in wheat, field weeds and corn, as well as the occurrence density and virus-carrying rate of gray planthopper. In late autumn and late spring and before corn sowing, according to the overwintering base number and virus-carrying rate of gray planthopper, the diseased plant rate of wheat and weeds, combined with maize planting pattern, the occurrence trend of maize rough dwarf disease was predicted timely and accurately to guide the prevention and control.

② should select suitable varieties: according to local conditions, we should select varieties with relatively good resistance, and pay attention to rational distribution to avoid large-scale planting of single resistant varieties. In 1970s, Yunong 704 had certain resistance to the disease, such as 50, Ludan 053, Nongda 108 and so on, which could replace the susceptible varieties such as Shendan 7, Yedan 53 and Yedan 22 in production. In areas where susceptible varieties have been planted for many years and are seriously harmful, it is particularly important to grow these disease-resistant (tolerant) varieties. In Qufu, maize hybrids Ludan 50 and Luyuandan 14 had better resistance to rough dwarf disease.

③ adjust the sowing date of maize: according to the occurrence law of maize rough dwarf disease, the sowing date should be adjusted in the areas where the disease occurs again, so that the most sensitive growth period of maize to the disease can avoid the epidemic period of adult gray planthopper and reduce the incidence. Spring sowing corn should be sowed early, generally in late April and early May, interplanting corn in wheat field should be postponed appropriately, generally 5 days before wheat harvest, shorten the symbiotic period of wheat and corn as far as possible, so as to achieve appropriate late sowing. There are mainly three maize planting patterns in Qufu: wheat intercropping corn, stubble corn and late sowing corn, among which wheat intercropping corn is the most serious, followed by stubble corn, and then late sowing corn. Spring sowing corn should be sown before mid-April, while summer sowing corn should be in early June.

④ clears weeds in time: roadside and field weeds are not only the provenance base of farmland weeds in the coming year, but also the overwintering and summer hosts of gray planthopper, a vector of maize rough dwarf disease. For the remaining weeds in the wheat field, weeding can be done manually before spraying, and the weeding effect can reach about 95%. The advantage of choosing soil treatment is that maize does not symbiosis with weeds at seedling stage, which reduces the activity space of gray planthopper, which is not conducive to the transmission of gray planthopper.

⑤ to strengthen field management: combined with fixed seedlings, pull out diseased plants in the field, concentrate on deep burial or burning, and reduce the infection source of rough shrinkage disease. Reasonable fertilization and watering, strengthen field management, promote the growth of maize, shorten the susceptible period, reduce the chance of virus transmission, and enhance the resistance and tolerance of maize.

⑥ eliminates virus provenance: corn rough dwarf virus overwinters mainly in wheat, Gramineae weeds and gray planthopper. Therefore, it is necessary to control wheat rosette dwarf disease, remove weeds in fields, fields and ditches, and reduce the population base of gray planthopper. When spraying, the weeds around the wheat field should also be sprayed, which can significantly reduce the pest population density. if necessary, 20 grams of non-tracer water agent or 45% Nongda water agent 550 ml / mu, 30 kg of water can be used to spray on the field edge of the field. kill weeds and destroy the living environment of gray planthoppers.

2. Chemical control methods.

Seed dressing with ①: coating and dressing corn seeds with internal insecticides can effectively control gray planthopper at seedling stage and reduce the spread of rough dwarf disease. When sowing, seed dressing with 2% seed coating agent can effectively prevent the harm of gray planthopper, at the same time help to cultivate strong seedlings and improve disease resistance of corn. After sowing, pre-budding soil treatment agents such as 40% atrazine water gel suspension, 50% du A mixture, 550-575 ml / mu per mu, and 30 kg of water were sealed.

② spraying insecticidal: if the rough shrinkage disease occurs in the corn seedling stage, the diseased plants should be removed in time, and according to the prediction of the situation of gray planthopper, 25% buprofezin 50g / mu should be used in time. In the 5-leaf stage of corn, it should be sprayed every 5 days for 2 times, and at the same time, the virus should be sprayed with 40% virus A500 times or 5.5% phytogermicin 800 times solution to control the virus. For individual plots where soil treatment herbicides are not effective in front of seedlings, 20% grams of herbicides can be sprayed between corn rows, 550 milliliters per mu and 30 kilograms of water. Be careful not to spray on corn plants. Ke Wuzhuan is quick to kill weeds. All weeds can die 52 hours after spraying, which can reduce the activity space of gray planthopper. 45% Roundup water agent can be sprayed on the edge of the field, but try not to use it between corn rows. So as not to cause drug damage to corn.

Maize rough dwarf disease is destructive, and once it occurs, it is difficult to cure. It is unrealistic to spray some kind of medicine on the diseased plant to make it return to normal, but as long as the combination of agricultural control and chemical control is achieved, the spread of the harm can be controlled.