Why are there more powdery mildew on apple trees?

Apple tree is the largest fruit tree planted in the north. As the title asks, there are more and more powdery mildew on apple trees at present. Are there any good suggestions and control methods?

Next, I will answer from three aspects: the symptoms of apple powdery mildew, the causes of more and more treatment of powdery mildew, and how to prevent it.

First of all, apple powdery mildew and its symptoms Apple trees are the main fruit tree varieties in the north, mainly planted in Shandong Jiaodong Peninsula, Liaoning Dalian, Shaanxi, Shanxi, Gansu and other places.

Apple powdery mildew is a disease caused by fungi, and its high incidence period is from April to June. The specific parts that mainly harm apple trees are seedlings, leaves, buds, flowers and young fruits. After infection, the buds grow slowly, the new leaves shrink and deform, and a white powder layer appears on the back of the leaves. The shoots were infected, the growth was inhibited, the internodes became shorter, the leaf edges rolled up, and the initial surface was covered with white powder. Powdery spot and powder are the most important distinguishing features of powdery mildew.

Pathogenic conditions and rules: the suitable breeding temperature of bacteria is about 20-25 degrees, and the humidity requirement is not high, and it is easy to get sick mainly in the dry period.

Second, the reason why powdery mildew is treated more and more is 1, and the medication cycle is incorrect.

Prevention first, many fruit farmers use drugs only when they see that the disease is serious and has affected the growth of crops.

2, the control agent is too single, resulting in drug resistance.

Single selection of myclobutanil or difenoconazole for control will produce drug resistance;

3. The awareness of powdery mildew prevention is not in place, and farmers do not accept new special fungicides.

Fruit farmers have been using old varieties of pesticides, and the control effect is average at present.

Third, how to prevent this situation? 1, pay attention to the pruning of apple trees, the diseased buds must be removed during dormancy, and the seriously ill fruit trees should be pruned again to reduce the amount of bacteria. After germination in early spring, the diseased leaves should be found in time and pulled out as soon as possible. 2. Strengthen field management, control field humidity and gout, and reduce illness; 3. Grasp the correct key medication period: prevention and control must be in place before germination, after blooming and after flowering; 4. Choose diversified fungicides and compound them as far as possible: such as difenoconazole, myclobutanil, pyraclostrobin, pyrazole, cardan, tebuconazole, ethirimol sulfonate, diethyl ether phenol, hexaconazole and other products are properly compounded to prevent drug resistance; 5. Choose more advanced chemicals: such as tetraconazole, ethirimol sulfonate, ningnanmycin and other products. Note: Be sure to go to professional retail stores to buy regular products, and follow the instructions and product manuals of professional retail stores.

To sum up, apple powdery mildew is not difficult to treat. As long as we avoid the disease, do a good job in field management, prune diseased buds and leaves in time, seize several key drug use times, find powdery mildew spots in time, use drugs as soon as possible, and achieve "prevention first, comprehensive prevention", we can minimize the harm of powdery mildew and realize a healthy harvest of apples!