Citrus canker causes leaf drop, fruit drop and branch dieback: how to prevent and control it

    Citrus canker, one of the major diseases of citrus, mainly attacks leaves, and also attacks branches and citrus fruit, causing leaf drop, fruit drop and branch dieback, weakening tree vigor and reducing citrus yield and quality.

Citrus canker

    Control methods:

   (1) Strictly enforce citrus quarantine. It is strictly forbidden to introduce diseased nursery stock, scions and citrus into disease-free areas; once found, burn them completely.

   (2) Establish disease-free areas and cultivate disease-free nursery stock. Choose a well-isolated place as a nursery, and it is strictly forbidden to bring in seeds and scions from diseased areas.

   (3) In diseased areas, inspect frequently, prune out diseased branches and leaves, and clear dead branches and fallen leaves from the ground to eliminate the pathogen. During the citrus growing period, spray for protection. For citrus nursery stock and young trees, spray once each at 20 days and 30 days after the spring, summer and autumn shoots sprout. Bearing citrus trees should be sprayed once each before flowering, after flower drop, and after the summer and autumn shoots emerge.

    The main agents include: 0.5:1:100 lime double-strength Bordeaux mixture, 50% Yejuning 500—1000 times solution, 25% Dikuzuo 500—1000 times solution, 50% Tuzhite or 50% Daisen ammonium 500—800 times, 20% synergized Shuangxiaolin 600—800 times solution, etc.

   (4) Control the emergence of summer and autumn shoots and keep the shoot periods consistent. The branches and leaves of citrus damaged by citrus leafminer create wounds that provide conditions for pathogen invasion, so citrus leafminer damage will aggravate the occurrence of citrus canker. Focus on controlling citrus leafminer and plant disease-resistant citrus varieties.