Wheat powdery mildew is also a common disease in wheat crops in our county. In recent years, wheat powdery mildew has been increasing year by year because of the increase of wheat population in the field and the improvement of water and fertilizer conditions in wheat fields. Barley, wheat and oats all occur, with large and heavy wheat.
(I) Occurrence and epidemic conditions
1 Variety resistance. Although there are obvious differences in resistance to powdery mildew in the wheat varieties currently planted, most disease resistance is not high, which is a prerequisite for the occurrence of wheat powdery mildew.
2 pathogens. There are 32 physiological races of wheat powdery mildew. The preponderant races that existed in various regions have strong virulence to local wheat varieties, which is the main basis for disease occurrence.
3 weather conditions. In the years when both the susceptible species and the bacterial source exist, the rapid rise in temperature in spring and the high humidity will be conducive to disease epidemics.
4 Cultivation Management. Water and fertilizer conditions are good, nitrogen fertilizer is too much, plants grow too dense, greed green long, poor ventilation and light transmission, or water and fertilizer conditions are poor, plant growth is weak, cell water shortage loses turgor pressure, disease resistance is reduced, and the incidence is heavy.
(B) Prevention and control methods: Planting disease-resistance varieties as the main, pharmacy and cultivation measures as the supplement, pay close attention to the common area, take into account the general area.
1 Planting disease-resistant varieties: It is the most cost-effective control measure.
2 Cultivation and disease prevention. Proper close planting, pay attention to the scientific collocation of nitrogen, phosphorus and potash. In large areas with high humidity, we must pay attention to trench drainage, reduce the humidity in the field, help the wheat grow robustly, and increase the resistance to disease; after wheat harvest, we must timely plough the stubble, remove the diseased bodies and self-producing wheat seedlings, in order to reduce the bacterial source of autumn seedlings. .
3 Chemical control
Seed treatment: In regions where the incidence of wheat seedlings is high, seed dressing of 20% of the seed weight of 20% of triadimefon can be used, which can effectively control the incidence of wheat seedlings, reduce overwintering germs, and treat both seedling stage rust and various smut diseases.
Field spraying: Generally, it is carried out before wheat booting to heading. The commonly used agents are mainly 25% carbendazim 500 times, 50% thiophanate 800-1000 times, 25% Triadimefon 35-50g per mu, or 20% Tetraining EC 50-75ml, watering 50-75kg spray, Generally spray more than three times, each time interval 7-10 days.
Three wheat stubble
Wheat aphid is a kind of pest that often occurs in wheat crops. It mainly consists of wheat long tube aphids, glutinous corn aphids, wheat bifurcations, and my county is mainly long tube aphids. The main host of wheat bran is barley, wheat, oats, and corn. The wheat bran can also harm rice and grass weeds (see Aphrodisias, Poa pratensis, etc.). Wheat bran sucks plant sap, affects crop development, but also spreads wheat yellow dwarf disease, yellowing leaves, dwarfing plants, reducing tillering, and seriously affecting yield.
(I) Occurrence of regularity The Maichang worms are born with finless worms or if they are in the leaves or sheaths of wheat plants and all kinds of grass weeds, to see winter maidens in the leaves of the maidens and bluegrass, but after the winter, If you don’t really enter the wintering state, if the weather is warm, you can still climb the wheat seedlings. Overwintering worms began to move in the warmer months of February and February of the following year. They first infested the leaves, leaves, sheaths and leaves of the lower part of the wheat. They grew up due to long tube shoots and were more resistant to moisture. They moved upwards with the elongation of the wheat seedlings. Focus on the panicle damage. During the grain-filling period of wheat, the longest tuber in the city of Maimai reproduces rapidly. During the period when the damage is most severe, the amount of maggots rises sharply and a large number of unborn females are produced. After wheat was harvested, it was relocated to reeds, foxgloves, and other weeds to reproduce on the corn and other crops. After winter seedlings were unearthed, they were gradually relocated to the wheat seedlings for breeding harm.
(b) Occurrence of weather and natural enemies
1 Climate When the average temperature exceeds 28°C or less than 6°C, the field population declines significantly. The population of worms rises at 7 -27°C and breeds fastest at 20 -22°C. Generally, in the year of October-November, when the weather conditions are low in rain and low temperature, the damage will be heavy. The high temperature of rain is not conducive to its occurrence.
2 natural enemies: Maitreya natural enemies have ladybugs, food reins, grasshoppers, parasitic bees, parasitic bacteria and so on. These natural enemies have a considerable inhibitory effect on the occurrence of wheat aphids.
(three) control methods
1 Agricultural control Combine fertilizer in the fall to clear the fields. Ditch and weeds near the wheat field to reduce the source of insects. Strengthen the basal fertilizer, use closely connected seedlings with spikelets, sow timely planting, and plant densely in close planting. Apply topdressing fertilizer in early spring to promote the robust growth of the selling plant, increase the ability to fight locust, and reduce damage.
(2) Suitable period of prevention and control of chemical control Before the wheat is grouted until it is milk-cooked, it is listed as a field for prevention and control when the amount of Pleurotus melanocarpa reaches 500. It is possible to use 50% anti-inferiority WP 15g per mu, and 40% omethoate EC 50ml. 20% to kill 20ml of sterile acid emulsion per acre and add 50kg of water spray.
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