May Fruit Growing Tips
Fruit trees require lots of care in May. Early May is a great time to fertilize young fruit trees if they have not had adequate growth rates in the past. Typically we expect to get 12”-18” of new growth each year on young apple trees. If not, then your tree may need fertilizer. The best time to fertilize fruit trees is early May or sometimes late April when the buds are swelling or just opened.
Here at Johnson’s Nursery, we sell an excellent slow-release fertilizer called Nutri-pac. This product is placed in the ground next to the root system at planting time. It will provide nutrients to the plant for about three years, is easy to use and has no fertilizer run-off issues. It will work well for fruit trees.
If you did not apply Nutri-pac at planting time, you can still fertilize with either a good liquid fertilizer or a granular fertilizer. Follow the directions on the liquid fertilizer. For granular applications, use 10-10-10 or similar granular product on hand. The big issue is not to over-fertilize with a granular product! More is not better. Fertilizer is a salt and will attract water. Applying too much granular fertilizer will cause your plant to wilt and burn. When applying a granular product on fruit trees, just apply on the soil surface around the dripline of the tree at the rate one would apply table salt on a good steak before eating. This will be a safe and inexpensive way to fertilize your fruit tree.
May is a key month to start a spray program on apples if you desire perfect fruit. Your first spray should be a fungicide application at green tip stage (when buds break and the first sign of green shows). Spray a second fungicide application 7 days later if tree is not yet in bloom. Starting at petal fall, apply a combination of fungicide/insecticide every 7-10 days thru mid- June. At that time, you can switch to a 12-14 day spray schedule until mid-August. Most home fruit growers use a home orchard spray mix that is a combination of one or more insecticides with a fungicide. Or, one could purchase the pesticides separately and mix together when spraying. Usually Malathion (insecticide) and Captan (fungicide) are what is present in most Home Orchard Spray mixes on the market. Please do not spray an insecticide when your apple tree is in bloom as you may harm the bees that are working so hard to pollinate your apple tree! Watch out for some Home Orchard Spray mixes on the market that contain the insecticide carbaryl (Sevin). This insecticide can act as a fruit thinner when sprayed on newly developing apples shortly after petal fall and cause some of the fruit to abort. Usually Home Orchard Spray mixes containing carbaryl have a warning on their label about this and advise how long to wait after petal fall before safely spraying but some fail to warn. I prefer to buy my insecticide & fungicide separately and mix it myself (better control) but it usually is more economical to use a pre-mix product.
The key insect/disease problems in May are apple scab, and plum curculio. Apple scab is caused by a fungus. This disease will show up as dark spots on the leaves and black lesions on the fruit. It is considered a cosmetic problem as it seldom is severe enough on the leaves to harm the health of the tree and the infected fruit is not harmful for human consumption. If the fruit is to be peeled and used for cooking once harvested, then scab is not a major issue. To prevent this disease, fungicide applications must be made prior to infection. The best way to prevent scab from being an issue is to spray in May-June. This is when the primary infection can take place if the fungus is present and the conditions are correct. If preventative applications are made now and prevent a primary infection from taking place, the chance of scab occurring later in the season is tremendously reduced.
Plum curculio is a beetle that causes feeding/egg laying damage on developing stone and pome fruits. While the damage is more severe on stone fruits (peaches, cherries ect) it will deform apples as well. The most common damage will be seen as a crescent shaped scar on the skin of an apple. Curculio season usually occurs late-May to late-June in our area. Spraying with an insecticide at this time will help control this pest. Unfortunately, I have not found Malathion to offer excellent control on plum curculio. Luckily curculio damage is primarily cosmetic on apples.
Paul Schwabe is a salesman in our Contractor Sales division. He holds a degree in horticulture and will be writing about some of his favorite and underused plants.