Steps to manage canker
Scientists have developed the following integrated approach to manage canker in cherries:
- Avoid interplanting new with old trees. Rain can splash inoculum from old trees onto the young, healthy trees.
- Do not use sprinkle irrigation on trees for the first three years. In late summer, reduce the amount of water applied for irrigation to harden off the tree so they are not as susceptible to winter injury.
- Avoid all types of injuries to trees—mechanical, insect, or frost. Paint trunks with latex paint to prevent sunburn.
- Delay pruning until spring, as late as May if possible. Avoid wet wounds. Less disease occurs in the summer.
- Remove diseased branches and trees from the orchard and destroy them to reduce inoculum.
- Plant resistant cultivars and rootstocks. Mazzard F12-1 is among the most resistant rootstocks; Rainier and Regina appear more resistant than Sweetheart and Bing.
- Avoid planting in frost-prone and slow-drying areas.
- Provide optimal soil conditions and balanced nutrition to get young trees off to a healthy start.
- Control weeds, especially grasses, to reduce inoculum levels.
- Pseudomonas has developed widespread resistance to copper. Use of copper fungicides may worsen the problem and should not be used.
- Test for and control nematodes before planting a new orchard. High populations of ring nematode have been associated with more bacterial canker.
- Avoid planting trees in wet conditions. Plant later in the spring when chances for dry weather are greater.
- Minimize the length of orphan stubs. Cut stubs close to the lateral. A recent heading study showed that longer stubs left above the topmost lateral increased the chance of gummosis and dying tissue problems.