What specific fungicide to use for tomato leaf spot

Leaf spot is a common disease of tomatoes, and it can infect leaves as well as petioles, fruit stalks and fruits. So, what are the specific fungicides for tomato leaf spot?

1. What are the specific fungicides for tomato leaf spot?

The specific fungicides for controlling tomato leaf spot include 25% copper ammonia complex aqueous solution at 500 times dilution, 77% Kocide wettable powder at 400-500 times dilution, 1:1:200 Bordeaux mixture, 50% thiophanate-methyl and sulfur mixed suspension concentrate at 500 times dilution, 50% thiophanate-methyl wettable powder at 600 times dilution, etc. A formulated fertilization technique can also be used, spraying Duoxiaohao at 4000 times dilution, or 1.4% sodium nitrophenolate aqueous solution at 7000 times dilution, to improve the disease resistance of the plants; after harvest, remove diseased residues and deep-plow in time.

2. What are the disease symptoms of tomato leaf spot?

Tomato leaf spot, also known as brown spot, infects leaves as well as petioles, fruit stalks and fruits. On the leaves, grayish-brown round or nearly round spots with a distinct edge, 1 to 10 mm in diameter, first appear; the diseased part becomes thin and sunken, with a glossy appearance, especially obvious on the underside of the leaf, which distinguishes it from other leaf spot diseases. Large spots sometimes show concentric rings, and in high humidity develop dark brown mold; when petioles and fruit stalks are infected, the spots are grayish-brown and sunken, and in high humidity black mold grows; the spots vary in size and are sometimes elongated.

3. What is the disease cycle of tomato leaf spot?

It mainly overwinters in the field as mycelium with diseased residues; when conditions are suitable, it produces conidia, which are carried by air currents and rain splash onto host plants, invading through stomata, with an incubation period of 2 to 3 days. The suitable temperature for the pathogen's development is 25 to 28°C, and the suitable pH is 6.5 to 7.5. High temperature and high humidity, especially rainy and hot seasons, make it prone to epidemics. In addition, damp vegetable plots, weak tomato growth, overly dense planting, poor ventilation and light penetration, or insufficient fertilizer lead to severe disease.

For tomato leaf spot, it can be prevented by understanding its disease cycle well, and if it does occur, timely treatment is all that is needed.