A Detailed Guide to the Latest Control Methods for Blueberry Canker
Blueberry canker is one of the most common diseases affecting blueberries. It occurs quite widely, and there is relatively more experience with its control. So what are the symptoms of blueberry canker infection, how do you identify it, in what season does it mostly occur, and what pathogen causes it? Then the characteristics of the pathogen and its transmission routes are all things we need to understand, so that we can more easily prevent and control the damage caused by canker.
1. Disease Conditions
The disease is caused by a fungus, generally spread by conidia carried by rainwater and irrigation water to multiple sites and causing infection. Seeds and farming operations can also carry the pathogen and spread it. The pathogen overwinters in diseased tissue and is the main source of infection. Generally, once temperatures rise again, it can resume reproducing and causing damage, and then the hot, humid period from May to June is the peak of disease occurrence. Infection mainly begins in April, with the pathogen invading through wounds and natural openings, but failure to take good freeze-protection measures in winter is the main trigger.
2. Disease Symptoms
The pathogen mainly affects the base of the upper branches of the current year's growth, after which lesions appear. The lesions look water-soaked and irregular; they are relatively small at first and then expand, encircling the entire branch. The lesions are clearly distinct from healthy tissue, and the lesions are red-brown or yellowish-brown at first before turning dark black later. Black spore spots form on the lesions. After being affected, the leaves turn brown.
3. Control Measures
1. Pruning
During the dormant period, prune away branches that have changed color, because they may be infected, so as to prevent occurrence. Provide sufficient fertilizer and water so the branches grow quickly. However, too much fertilizer is also harmful to blueberry growth. If diseased branches are found in the orchard, prune them promptly and carry them out of the orchard to be buried deep in one place or burned. Disease is likely to occur in winter when freeze protection is poor, so branches should be checked and pruned frequently in winter.
2. Variety and Site Selection
When planting blueberries, choose excellent varieties that are relatively disease-resistant and highly adaptable. The planting stock should be virus-free stock cultivated through special techniques. The planting site should be in a relatively high location far from rivers, requiring dry, breathable, fertility-retentive loam that is not sticky and heavy.
3. Chemical Treatment
When disease is found, prune first and spray promptly. If severely diseased plants are found, they can be pulled out directly, the soil replaced, and the soil and surrounding environment disinfected. Spraying should be done on sunny days, and re-sprayed if it rains. Mainly spray a 500-fold dilution of 20% prothioconazole suspension concentrate. In addition, if the disease occurs across the board, every effort should be made to save the plants. Generally, the above agent should be applied to the diseased areas; for large lesions, it may be necessary to scrape off the lesions before treatment. Apply once every three days; in severe cases, it can be applied once every other day, applied continuously three to four times, and it will basically improve.
Among the common blueberry diseases, canker occurs widely, and it is also the main disease that frequently requires control. The above content briefly introduces the occurrence and control of the disease, for reference. Thank you for reading.