Spraying Blueberries and Apples

Asked August 27, 2013, 2:07 PM EDT

I have some apple tree's and blueberry bushes and do not know when and what to spray them with. I know there are fungicides and pesticides and fertilizers to use but can you tell me what works best, when to apply these items and where to purchase them from?
My apple tree's have black spots on the leaves and only 1 apple on the tree's I have. I sprayed them generously several times with a Menards fungicide/pesticide concentrated mix but didn't seem to help.

Allegan County Michigan

1 Response

In order to get good control of insect pests and diseases you need to know what you are trying to control and apply the controls before the insect or disease gets started. Pesticides sprays will not make the problems go away. The fruit tree spray mix should work if you start early enough.
Let's start with the apples. Apple scab is an important disease that infects the leaves and fruit causing black spots on the fruit and leaves and also causes the leaves to fall off and weaken the tree over time. You need to apply fungicides to control scab from gree tip when the leaves first emerge until about a month after bloom when the fruit are about 1.5 inches in diameter and the surface of the fruit is waxy. Scab spores are released every time it rains and if the leaves are wet long enough begin the infection. You need to apply the fungicides every 10 days to be sure that the new leaves are covered with fungicide. You need to spray more often if we have a rainy spring. After bloom, when you have fruit you need to protect the fruit from insects that will attack it. Generally an insecticide is applied every 2 week,s from 2 weeks after bloom to Labor Day. There are 4 major pest that attack apples in Michigan and not all are out at the same time but usually one or two are out all season long. If you now which pest you have you could drop some sprays but since you don't you need to cover all the times.
The Blueberries are generally easier There are some fungal diseases tha attack the bush early but if you are not somewhere there are lots of blueberries you probably do not have this disease. After bloom you need to spray with a fruit mixture with both an insecticide and a fungicide to control the insects that attack the fruit right after bloom and the fruit rots. One spray right after bloom and another 10-14 days later will be enough. You need to spray of fruit flies and blueberry maggot as the fruit starts to ripen. You should spray every week with malathion to control the fruit fly. I would suggest you spray when the fruit starts to ripen and pick 5 to 7 days later and then spray after you pick and wait several days to pick again. You should spray after a rain.
You do not need to worry that you do not have access to commercial pesticides. The materials in homeowner sprays are diluted so you can use them safely in small plantings and are similar to commercial materials and should provide control. The spray programs I have recommended are similar to what commercial growers use to control insect pests and diseases.