MySheen

Identification and control of black spot of rose

Published: 2024-12-29 Author: mysheen
Last Updated: 2024/12/29, The disease is common and does serious harm, resulting in a large number of fallen leaves of rose and huge losses. The pathogen is a fungus of the genus Actinomyces. First, at the beginning of symptom recognition, brown radial disease spots appear on the leaf surface, and then gradually expand into round or near-round disease spots, with a diameter of 412 mm; in severe cases, the lower leaves fall off in the early stage, gradually spread upward, and eventually the upper leaves will lose light. Rainy and humid is the main condition for spore production, there are water droplets on the leaf surface, and at the appropriate temperature, it can invade in 6 to 10 hours and appear symptoms in 3 to 6 days.

This disease occurs widely and seriously, causing a large number of rose leaves and huge losses. The pathogen was actinomycetes belonging to the genus Actinomyces.

I. Symptom identification

At the beginning of the disease, brown radial spots appear on the leaves, and gradually expand into round or nearly round spots with a diameter of 4~12 mm; in severe cases, the lower leaves fall off early and gradually spread upward, and finally the upper leaves will fall off. Rain and humidity are the main conditions for spore production. There are water drops on the leaves, and under appropriate temperature, they can invade in 6~10 hours, and symptoms appear in 3~6 days. The yellow rose has poor disease resistance.

II. Prevention and control techniques

1. Field cultivation, selecting disease-resistant varieties.

2. Cut off diseased branches in winter, clean up fallen leaves in the field or basin at ordinary times, and burn them intensively.

3. Pay attention to spraying protection. Starting from April, spray 1:1:160 Bordeaux mixture once a week; spray Bordeaux mixture or 50% carbendazim WP 500~800 times solution from June to August; or 75% chlorothalonil WP 500 times solution; or 70% mancozeb WP 500~600 times solution.

 
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