Managing dormant fruit trees
- Frank Becker, OSU Extension Wayne County
- March 15, 2022
- 693
Fruit tree care and management do not simply stop when the leaves fall off the trees late in the year. Fruit tree care is a year-round job, and in order to get the best performance out of your fruit trees, it’s important certain tasks are done at the right times.
With the trees dormant now, it is a good time to look at some disease-management options. When we talk about dormancy, we are looking at the time frame between when the tree drops the leaves in the fall and when buds begin to swell in the spring. With diseases such as peach leaf curl, applying a fungicide while the tree is dormant is recommended. Thorough and complete coverage of the tree is needed to ensure complete control.
Typically, the top 3-5 feet of a tree are hardest to reach, and this is the area in which we see the fungicide lose efficacy, either due to low coverage or just simply not being reached by the application. Although applications are most effective when applied in the late autumn after leaf fall, it’s important to apply the fungicide before the buds on the trees start to swell, which will start to happen before too long.
There are other dormant sprays to help control diseases such as Phytophthora crown/root/collar rot or bacterial spot/canker, and these are typically applied before growth starts in the spring. There also are sprays — for example, copper products for fire blight — that are applied right before growth starts in the spring and when temperatures are above 45 F.
Dormant oil is regularly used on apple, pear and plum trees to aid in control of scale and aphid pests, at a rate of 2%, which means 2 gallons of horticultural oil per 100 gallons of water. This should be made as a dilute application, with plenty of water so all bark is treated. As the word “dormant” implies, this spray should be applied before the buds swell or before new growth (green tip stage) starts in the spring. If applied after growth starts, the new tissue can be damaged by oil at this rate.
Application should be done when temperatures have been above freezing (above 35 F) the day before the application and when the weather forecast calls for nonfreezing temperatures for at least 24 hours after application. For this area, usually late February to early March is a good target period.
Oil also can be used for control of mites, but for best control of mites, it is more effective if application is delayed until late in the “delayed dormant” stage. When oil is applied at the half-inch green bud stage or no later than the tight cluster bud stage, the rate can be dropped to 1%, meaning 1 gallon of horticultural oil per 100 gallons of water. Oil at this time should still be applied in dilute form so all of the bark surface is treated.
An important note: for all fruit crops, if liquid lime-sulfur is used, it should not be sprayed with, or in close timing (one week) with an oil spray as tissue damage can result.
Regardless of your level of involvement with chemical application or the scale of the operation, the most important thing for you to do is to read the product label. The label is the law. More information on products and recommendations can be found in the “Midwest Fruit Pest Management Guide.”
Chemical-control options are not the only disease-management tool you should use. Cultural control and sanitation around the fruit trees also are important. When referencing “cultural” controls, this refers to the management techniques that are implemented when working with a crop and the associated diseases and pests.
A lot of diseases over winter on leaf litter and dropped fruit on the ground. As a disease-management strategy, implementing a cultural-control practice of cleaning up and disposing of leaf litter or fruit residue can reduce the amount of inoculum around the tree, in turn reducing the disease pressure from those diseases.
Pruning also is an important part of winter management, and likewise, as you prune, it is important to burn or dispose of the pruned branches. During winter pruning you can target diseased branches and help reduce the impact of diseases such as fire blight or black knot in your trees.
Now is the time to get your fruit-tree orders together and prepare to get the trees in the ground in March or April. Allowing the roots to get established in soil that isn’t frozen while temperatures are still cool and while the ground still has adequate moisture will help avoid stress on the tree when the top growth is initiated by longer days and warmer temperatures.
Fruit trees typically need to be fertilized once a year in early spring before growth starts. It is very important to do a soil test to determine accurate fertilizer recommendations. Generally speaking, a common fertilizer recommended for fruit trees is one with an analysis of 12‑12‑12 or 10‑10‑10. However, fertilizers of other analyses also can be used.
The rate of application needs to be adjusted based on soil-test analysis and recommendations. More information on specific requirements, recommendations and guidelines can be found in the “Midwest Home Fruit Production Guide,” publication by the Ohio State University.
Competition of nutrients and moisture is one of the main reasons to control and limit the amount of vegetation under fruit trees. Reducing this vegetation also limits the favorable conditions and habitat available for diseases, insects and rodents. Weeding is not a fun job, but a year-round one nonetheless.
Hopefully, this is enough to keep you busy until the warm days arrive. The trees will be budding and blooming before we know it. If you are interested in purchasing any of the publications mentioned in this article, give your county OSU Extension office a call or visit www.extensionpubs.osu.edu to find a full listing of all the OSU Extension publications.
Frank Becker is the Wayne County OSU Extension agriculture and natural resources integrated pest management program coordinator and a certified crop advisor and may be called at 330-264-8722 or emailed at becker.5872osu.edu.