Lincheng County is located in the northwestern part of Xingtai City in the southwest of Hebei Province. It is a warm temperate sub-humid continental monsoon climate zone with an average annual temperature of 13.5 °C and an average annual precipitation of 605 mm. The county is a large county for planting thin-skinned walnuts. The "black-skinned walnuts" generally occurred, which seriously affected the yield and quality of walnuts. Therefore, how to effectively solve the early fall of black-skinned walnuts, the phenomenon of blackening of the nucleus has become one of the primary problems solved by the local walnut industry. A set of solutions to solve this problem is presented below.
1 Cause
There are two main reasons, one is disease, and the other is pests, as follows:
(1) The harm of walnut limb moth
In June of each year, the newly hatched larvae of the limbs moths will be drilled into the walnut skin to feed them. In the initial stage, the black skin of the walnuts will fall off, and the damage will lead to the drying of the walnuts and walnuts.
(2) The harm of walnut fruit weevil
In May of each year, the walnut larvae will penetrate into the walnut skin and harm the nuts, causing the fruit to become black and fall off.
(3) Hazards of walnut anthracnose
The high incidence of walnut anthracnose is from June to August. The brownish brown or dark brown lesions appear on the skin of the walnut. As the condition worsens, the fruit will turn black and rot, causing fruit drop after early damage. The germ is mainly transmitted by wind and rain and insects.
(4) Hazards of walnut black spot
Walnut black spot disease is a bacterial disease, and the damaged peel will produce brown water-stained small spots at the beginning. As the disease worsens, the lesion will sag deep into the nuts, causing the fruit to become black and rotten and the nuts dried up.
2 Preventive measures
(1) Before germination: plough the land under the tree, eliminate the overwintering walnuts and lift the moths; evenly spray 3 to 5 Baumeite sulphur mixture to control walnut anthracnose, walnut black spot, pest eggs and mites, etc. .
(2) At the beginning of May, the whole garden sprayed 2.5% beta-cypermethrin EC 2000 times solution and 75% chlorothalonil wettable powder 600 times solution to prevent pests such as walnut long-legged elephants and walnut anthracnose, walnut black spot disease and other diseases. In the second half of the year, the whole garden will spray half a quantity of Bordeaux mixture to prevent diseases such as walnut anthracnose and walnut black spot.
(3) In mid-June, the whole garden was sprayed with 25% chlorpyrifos No. 3 suspension agent 1000 times liquid and 50% carbendazim WP 600 times liquid to control walnut limb moth and walnut anthracnose and walnut black spot.
(4) In mid-July, the whole garden sprayed 70% thiophanate-methyl WP 700 times or 77% tainable 600 times liquid to prevent walnut anthracnose and walnut black spot.
(5) After harvesting the walnuts, thoroughly clean the diseased leaves, diseased fruits and diseased branches, and bring them out of the garden to bury or burn them, eliminate the overwintering bacteria and pests; after harvesting the clear garden, apply the organic fertilizer in the whole garden, and fertilize the soil after fertilization. Watering, enhancing the tree's potential and improving disease resistance.
(6) 5% lime water can be sprayed during high temperature in summer to prevent sunburn; when the winter is cold, the trunk is white and frost-proof.
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