DIY Network

Diseases, Pests and Harvesting Tips for raising a healthy apple crop From "Fresh From the Orchard" episode DFFO-112

Disease management goes on all year. Try to prevent disease problems by using good cultural practices such as selecting disease-resistant varieties, pruning and training properly and controlling weeds.

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As for weeds, weeds or lawn grass should not be allowed to grow right at the base of the tree (figure A): they compete with the tree for water and nutrients, and they harbor insects that are harmful to the trees.

Keep weeds at bay by mulching around the base of the tree, but never let mulch pile up around the trunk, where it can create the perfect environment for decay. By keeping a good ring of mulch around a tree, you'll also avoid one of the most common apple-tree hazards: bumping and scraping the tree trunk with a lawn mower (figure B)!

Figure A

Figure B

Fire Blight

Figure C

Fire blight is a common bacterial disease associated with apples, crabapples and pears. The primary symptom of fire blight is tips of branches' suddenly turning black and brown, as if they were scorched or burned (figure C).

If you notice symptoms of fire blight, prune out and destroy the infected branches. Make pruning cuts 4" to 6" below the dead area of the branch, cutting into healthy wood, and be sure to sterilize the pruning shears between each cut. Because at the base of the dead wood there's a canker that oozes out the harmful bacteria, it's important to destroy the prunings.

Other diseases are also prevalent, especially in hot, humid areas of the country. Where diseases are a particular problem, a spray program is a must for a good apple harvest. Check with your local extension agent to get a recommended spray program for apple trees in your area.

Brown rot is a fungal disease that affects apples (as well as pears, plums and most other cultivated tree fruit). Dispose of all damaged fruit and dispose of dead shoots and mummified fruits.

Frost rings are marks that occur when freezing temperatures damage the skin but don't last long enough to kill either the blossom or the fruit.

Harvesting

When deciding when to harvest apples, remember that "mature" and "ripe" mean two different things: mature fruit can still ripen once it's picked from the tree; ripe fruit is ready to eat.

Figure D

In general, apples are best harvested when they are sweet (or tart, depending on the variety). They should also be juicy and crunchy; if they're starchy and dry, they need some more time on the tree. Another trick for knowing when an apple is mature is to cut it open and look at its seeds. The seeds should be very dark brown or black (figure D).

When picking apples, handle them carefully. Remove the fruit from the tree by pulling upward and outward while twisting slightly. Another tip is to pick apples with their stems attached; otherwise they will not store well.