APPLE SCAB CONTROL

Apple scab is a frequent problem for any Lapeer, MI landscapes with crabapple trees. The apple scab fungus may be found growing on the crabapple fruit itself, the leaf, leaf and fruit stems, or the green twigs of the crabapple. I’m surprised at how many Lapeer homeowners I speak with that are unaware that apple scab is a tree disease that can be controlled with the right treatments.

Apple scab is easy to diagnose, especially if it is on the leaves or the fruit of your crabapple tree. Anyone with a computer can find numerous photos of apple scab infected leaves and confirm that their crabapple tree has apple scab.

As a resident of Lapeer I see numerous examples of crabapple trees infected with apple scab fungus. Apple scab is caused by the fungus Venturia inaequalis, which also can affect apple, hawthorn, mountain ash, and firethorn. Because apple scab is a fungal disease, fungicides are used to control it. Apple scab can be hard to prevent if fungicide treatments are not started at the right time. To control primary infections you want to start the fungicide program shortly after the crabapples start to leaf out, which is usually around mid-April in Lapeer. I’ve found that the best control of apple scab is obtained when at least three fungicide treatments are applies throughout the spring.

Apple scab spores are always present in our environment, so it would be necessary to have these fungicide treatments applied every spring. If you need more information on apple scab call us at 800-724-6680 or you can find out more information about apple scab at: http://www.owentree.com/apple_scab.html

WHAT INSECTS ARE CONTROLLED BY DORMANT OIL TREE SPRAYS?

Spraying trees with dormant oil is one of the first applications we apply. This tree spray is designed to control overwintering insect adults and eggs. Dormant oil can also be used at a lower rate after trees leaf out. Dormant oil tree sprays are desirable to use whenever possible because they control some plant-feeding insects with little impact on beneficial insects. A frequent question we receive from homeowners is “What insects do dormant oil tree sprays control?”

Here is a list of common landscape insects and the level of control that can be expected with dormant oil tree sprays:

INSECT / MITE	CONTROL
Apple aphid on crabapple	Poor
Birch aphid	Poor
Cottony maple scale crawlers	Good
Eastern tent caterpillar	Poor
Elm leaf beetle eggs	Good
Elm leaf beetle larvae	Poor-Good
Euonymus scale crawlers	Good
European pine sawfly	Good
Golden oak scale crawlers	Good
Honeylocust leafhopper	Good
Honeylocust plant bug	Good
Honeylocust spider mite	Poor
Imported willow leaf beetle	Poor
Japanese beetle adults	None
Pine needle scale crawlers	Good
Pine tortoise scale crawlers	Poor-Good
Spruce spider mite	Poor
Sycamore lacebug	Good
Sycamore plant bug	None

None = 0-20% control

Poor = 20-60% control

Good = 60-100% control

The type of landscape plants on your property dictates whether or not your plants would benefit from a dormant oil tree spraying. If you’re not sure if a dormant oil spray would help your plants give us a call. We will have an ISA Certified Arborist inspect your plants and leave you written recommendations on what type of insect, disease, or mite treatments you may need to keep your trees and shrubs free of damaging pests.

CONTROLLING DIPLODIA TIP BLIGHT IN BLOOMFIELD HILLS

Diplodia tip blight is a very common fungal disease on pines in Bloomfield Hills. Austrian pine, mugo pine, and Scots (scotch) pine are the pine species most commonly infected with Diplodia tip blight.

Typical symptoms of Diplodia tip blight include dieback of the growing tips - hence the disease name. The fruiting bodies of Diplodia tip blight can easily be observed since they appear as pepper sprinkled over the surface of woody tissue. During a severe outbreak of Diplodia tip blight, a high percentage of the tips of a particular tree may be affected and will give the tree a brownish cast. Expanding buds, elongating candles or entire branches may be affected. Occasionally, only needles will be blighted. Affected needles remain on the tree, and in some instances entire trees may be killed. Diplodia tip blight can be confused with other problems such as the European pine shoot tip moth.

Diplodia tip blight fungus overwinters as maturing reproductive structures on cones, dead needles, or the needle sheath. Reproductive structures release millions of spores which may be splashed to emerging growth and cause infection. Two year old cone scales are an efficient source of fungus spores for infection. This is why mature pine trees (20 plus years) with abundant cones are most severely affected.

Controlling Diplodia tip blight without chemical fungicides is virtually impossible. A proper planting site and reduction of stress can reduce the severity of Diplodia tip blight. Pine trees infected with Diplodia tip blight should be periodically fertilized to maintain their health. Pruning infected pine trees will help the appearance of the tree but will not reduce Diplodia tip blight activity to any significant extent.

Fungicide applications are necessary to reduce the level of Diplodia tip blight activity. The first application should be made just before or during bud swell. This time will vary from year to year, and with the pine species, but is usually around mid-April in Bloomfield Hills. A minimum of two fungicide treatments should be applied, but better control of Diplodia tip blight will be obtained with a third fungicide treatment.