Control Methods for Rosetwig Dieback Disease
The editor will share with you some related experience of the rose clinic, the control methods for rosetwig dieback disease, and the editor will introduce the following methods to you.
Symptoms
Rosetwig dieback disease is limited to ulcer spots on the stems, initially appearing as small purple-red spots on the stems, which expand and deepen in color with more distinct edges. The center of the spots turns from light brown to grayish-white. The red-brown and purple edges around the lesions contrast sharply with the green of the stems. The conidiophores of the pathogen appear as tiny projections. As the conidiophores grow, the epidermis on top of them shows longitudinal cracks, and black spore masses seep out when it is humid, which is a characteristic symptom of this disease. In severe cases, the lesions quickly encircle the branches, causing the upper part to wither and die, turn black, and spread downward and sink.
Cause
The pathogen belongs to the genus Microsphaeropsis of the Coelomycetes, Sphaeriales order. The conidial apparatus is embedded under the epidermis of the branches, flattened spherical, with a black wall and a diameter of 180-250 micrometers. The conidia are nearly spherical, short椭圆形, or ovate, measuring 2.5-4.5 x 2.5-3.0 micrometers, colored. The conidiophores are short and colorless.
Routes of Infection
The rosetwig dieback disease pathogen overwinters in the diseased tissue of the plant as conidial apparatus and mycelium, serving as the initial infection source in the following spring. The pathogen is spread by wind and rain, mainly entering through wounds, especially pruning wounds or insect damage, and grafted seedlings can also be infected through the grafting joint.
Control Methods
1. Manual Control - Prune and burn diseased branches in winter. Pruning should be done on sunny days for easier drying and healing of the wounds. Injured branches after typhoons should also be pruned promptly. The cut should be as close to the axillary bud as possible and should include part of the healthy branch.
2. Chemical Control - After pruning, apply a Bordeaux mixture of 1:1:15. During the growing period, you can also spray a 50% wettable powder of thiophanate-methyl 700 solution, or a 50% wettable powder of carbendazim 1000 times solution, or a mixture of 0.1% zineb and 0.1% benomyl.
The above information on the control methods for rosetwig dieback disease is provided for your comprehensive understanding and reference!