Control methods of Potato Leaf Blight

Potato leaf blight mainly harms its leaves. In most cases, the senescent leaves in the lower part of the potato plant begin to develop in the middle and later stages of potato growth. At the beginning, the leaves will show green-brown necrotic spots, and sometimes they will infect stems and vines. Amorphous grayish brown necrotic spots will be formed in the late stage of the disease. Let's take a look at the prevention and control methods of potato leaf blight.

Harmful symptoms

Potato leaves infected, from near the leaf edge or leaf tip, the initial formation of green-brown necrotic spots, and then gradually developed into nearly round to V-shaped grayish brown to reddish brown large necrotic spots, with no obvious wheel lines, the outer edge of the disease spot often faded to chlorosis, and finally the diseased leaves were necrotic and scorched, sometimes a few dark brown spots (that is, the conidium of the pathogen) could be produced on the disease spot. The stem vine is infected with disease, forming amorphous grayish brown necrotic spots, and small brown spots can be produced in the diseased part in the later stage.

Occurrence characteristics

Potato leaf blight is caused by the infection of the fungus Alternaria alternata. The pathogen overwinters in the soil with sclerotia or hyphae along with the diseased tissue, and can also survive the winter on other host residues. When the conditions were suitable in the next year, Rain Water splashed the ground bacteria on the leaves or vines to cause the initial infection. After the disease, the disease produced sclerotia or conidia and carried out repeated infection with the help of Rain Water, resulting in the spread of the disease. Warmth and high humidity are beneficial to the occurrence and epidemic of the disease.

Prevention and cure method

1. Agricultural prevention and control: choose more fertile plots for planting and reasonable close planting.

2. Strengthen the management: increase the application of organic fertilizer and apply phosphorus and potash fertilizer properly. Timely watering and topdressing in the later stage of growth to prevent plant premature senescence.

3, chemical control: spray prevention and treatment at the initial stage of the disease, the medicament can be selected as 600x solution of 70% methyl topiramate wettable powder, or 600x liquid of 70% mancozeb wettable powder, or 1200 times liquid of 50% prohydantoin suspension, etc.