What is walnut branch blight?

What is walnut branch blight? What method can prevent and cure walnut branch blight please introduce: first, the symptom mainly harms the branch and stem of walnut tree, causing withered branches and withering, and in serious cases, a large number of branches withered and the yield decreased. The disease begins with the young twigs and then spreads down to the trunk. The cortex of the damaged branches was dark gray at first, then light reddish brown, and finally dark gray. And formed a lot of small black spots (that is, the pathogen conidia disk), the leaves of the infected branches gradually turned yellow, fell off, and the branches died. When the humidity is high, the disease produces a large number of black short columns (that is, conidia). 2. The pathogen Melanconium oblongum Berk called Alternaria nigricola, which belongs to the subphylum of semisporium. The conidium disk buries the host epidermis, then breaks through the epidermis, and the conidium peduncles are densely distributed on the conidium disk. Light gray, conidia bearing the tip of the sporophore, ovoid to round, mostly obtusely round at both ends. Some are slightly pointed at one end and dark brown. Third, the route of transmission and disease conditions of pathogens are mainly conidia or mycelium overwintering in branches and tree trunk diseased parts. The conidia produced at the right time in the following year spread by wind, rain or insects and invaded from the wound. The fungus belongs to weak growth bacteria, and walnut trees or branches with weak growth are easy to get sick, and the disease is serious in early spring or frostbite years. 4. Control methods 1. Biological control: (1) increase the application of organic fertilizer to enhance the tree potential and improve the ability of disease resistance. (2) cut off the diseased branches in time during the growing season and bury them deeply or burn them. (3) White tree trunk in autumn to prevent frost injury. (4) when the main disease occurs, scrape off the disease spot, disinfect the wound with 1% copper sulfate solution, and apply wound protective agents such as treatment healing ointment. 2. Chemical control: from June to August, spray control with 1000-fold solution of 70% methyl topiramate wettable powder or mancozeb wettable powder, once every 10 days, 3-4 times continuously, and the effect is good. Click to get more walnut planting techniques click to get more fruit planting techniques