Disease prevention and control of Parthenocissus tricuspidata

powdery mildew:

The disease can occur from seedlings. It basically harms the entire ivy plant. Small yellow spots begin to appear, and then develop into oval spots with a white powdery mold layer on the outside, usually more on the back of the body. Mildew spots are scattered individually in the early stage, and then unite to cover the entire page, seriously affecting photosynthesis, interfering with metabolism, and causing premature aging.

[Pathogenesis]

The pathogen cannot survive the summer in plain areas, and in autumn it is spread through the air to the plain wheat seedlings, causing disease. There are two main conditions for the occurrence of an epidemic: large-scale planting of infected varieties and suitable environmental conditions. Generally, when excessive fertilizer is applied, the wheat plants grow vigorously and become weak, the field humidity is high, and the disease becomes more serious. The disease usually appears in March and April, and as the temperature gradually rises, the disease rate increases rapidly and begins to spread under certain conditions.

[Prevention and treatment methods]

Agricultural measures: First, plant varieties that are resistant to disease; second, cultivate rationally and apply fertilizers appropriately.

Chemical control: First, mix the seeds with chemicals, using the same method as wheat smut; second, control should be carried out in spring and autumn.

Leaf spot:

① Brown spot disease, infects a large area. The spots on the leaves are oval in shape, which then increase in size and develop ring patterns. The spots on the stems and petioles are dark brown and appear in long strips.

②Black spot disease. Small black round spots appear on the leaves, which then expand into irregular patches with slightly raised edges and small black spots scattered on both sides.

③Dead spot disease. There are oval and long light reddish-brown spots on the leaves, which later expand into irregular patches with black spots on them.

【Pathogenesis】：

The leaf spot pathogen overwinters with the diseased body and infects the host during the following year's disease period depending on the climate. Three types of brown spot diseases occur in all seasons. Poor ventilation or excessive humidity can contribute to the disease.

【Prevention and treatment methods】:

If in a greenhouse, soil replacement can be carried out for prevention and control.

Ivy should not be sprayed, and should never be treated with spraying.

Start spraying at the beginning of the disease to prevent it from spreading. Pay attention to the alternating use of drugs to prevent the bacteria from developing drug resistance.