Jonagold is a cross between Jonathan and Golden Delicious apples. It produces yellow fruit with red streaks or blush and can be used for cooking or eating fresh. Jonagold, like most apple trees, needs another apple variety to pollinate it. Otherwise, the tree won't set edible fruit. Unfortunately, Jonagold won't return the favor, as its pollen is sterile. Thus, you'll need at least two other apple trees varieties that bloom around the same time to get fruit from all three varieties. Gala and Empire apples are compatible with Jonagold. Jonagold care is the same as for other apple trees.
Contact your extension office to discover diseases and pests attacking apple trees locally. Jonagold is especially vulnerable to fireblight.
Remove nearby red cedar trees, if possible, to prevent cedar apple rust.
Learn about central leader training (see Resources), which results in a pyramid shaped apple tree. Lateral branches are removed or trained so top branches don't shade lower branches.
Prune in very late winter. Remove dead or damaged limbs. A neglected tree should be pruned gradually over three years.
Test soil through your extension office every one to three years for nutrients and pH, which should be 6.5 to 7.
Fertilize in spring, using the results of the soil test as a guide. (Absent a test, use 1 pound of 10-10-10 fertilizer per tree in the first year, adding a pound per year until you reach about 5 pounds.)
Broadcast lime, if necessary, to raise pH. Water it in.
Water about an inch every two weeks including rain. You can measure water by putting out a marked container.
Spray the fungicide/insecticide according to product directions about every 2 to 3 weeks.
Rake leaf and apple debris from beneath trees.
Weed about a yard out from the trunk.
Repel deer with soap bars hung from branches or by fencing, rabbits by wrapping the bottom 12 inches of trunk with hardware cloth, rodents by traps and birds with noisemakers or netting.
Thin fruit when they're about marble-sized. Space fruits about 6 inches apart.
Thin trees judiciously no later than July's end, removing current vigorous growth interfering with the tree's pruning plan. Cut shoots flush to the nearest branch.
Harvest fruit as they mature or ripen. The color of the side not facing the sun is called the ground color. It should be yellow in mature Jonagolds.