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Insects & Diseases

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General Information

Before you can prevent or control an insect, pest, or disease problem, you should identify the culprit. As a starting point, if a plant appears healthy, it probably is healthy, and there is no need to spray. If a plant appears unhealthy, the cause could be "cultural" and involve the care of the plant rather than an insect or disease: too much water, too little water, not enough fertilizer, too much fertilizer, poor drainage, root disturbance, hot drying winds, or cold can affect the health of the plant.

But the problem could also be due to insects or disease. Examine the plant carefully. Check both the top and underside of the leaves, the stems, and the branches. Look for adult insects, webbing, eggs, larvae or pupae. Are there obvious signs of its being "eaten"? If the culprit is nowhere to be found during the day, go out with a flashlight and check at night. Check around the roots.

Consider the frequency and amount of water the plant has been receiving. Generally it is better to water deeply (to the depth of the roots) and less frequently. Irrigation systems are great for turf but too frequent and too little for woody plants. Frequent, shallow watering will result in a shallow root system which is less able to withstand periods of drought.

Check for physical damage. Does the part of the tree or shrub which is wilted or discolored have a break or split lower down on the branch? Has it been girdled by a guy wire, rope or chain? Has a lawn mower injured the trunk? If a plant has a case history, such as birch leaf miner, you might want to take preventive measures. A heavy infestation last year might warrant the use of a systemic as a soil drench this year. When dealing with pesticides, keep in mind that some insect sprays (such as malathion) are "contact" insecticides. That means that they will only be effective in killing the insect if the spray makes contact with the insect at the time of application. Malathion cannot be used as a "preventive" at the beginning of the growing season when no insects are present. Nor can it be used once an insect has taken such protective measures as rolling itself up in a leaf, or forming a gall around itself. Malathion is not effective at temperatures below 20C.  Also note that both malathion and carbaryl (Sevin) are extremely toxic to bees and are best not used when fruit trees are in blossom. They can kill the pollinating bees and prevent pollination. Using these chemicals at night or in the evening when bees are not present is also an alternative. Sevin also acts as a thinning agent and may reduce fruit set if applied to fruit trees during or soon after flowering.

Other insecticides, such as dimethoate (Cygon or Lagon) are termed "systemic." That means they travel through the system to all parts of the plant tissue, and when the offending insect chews on the plant he ingests the insecticide and is killed. Systemic insecticides (like all other pesticides) should be used with caution, and only according to the directions on the label.  Also consider less toxic alternatives to pest problems such as insecticidal soaps and dormant oil sprays.  Above all, READ THE LABEL!!

West Nile Virus

The City of Birmingham has taken proactive measures to prepare for a potential West Nile outbreak. While the City has been treating catch basins and areas of standing water on public property since 2002, the Department of Public Services recently researched and selected a more effective treatment option due to pre-season indicators.

The new treatment, Natular XRT, increases the effectiveness of the application which destroys the mosquito larva and prevents mosquito emergence. To date, the program has been very successful. According the Centers for Disease Control, there have been just five cases of West Nile Virus in all of Oakland County so far this year.

The Oakland County Health Division encourages residents to take the following steps to avoid the West Nile Virus and other mosquito-borne illnesses:

  • Maintain window and door screening to help keep mosquitoes out of buildings
  • Empty water from mosquito breeding sites such as buckets, unused kiddie pools, old tires or similar sites where mosquitoes lay eggs
  • Avoid being outdoors at dusk and dawn when mosquitoes are most active
  • Wear light colored, long-sleeved shirts and long pants when outdoors
  • Apply insect repellents that contain the active ingredient DEET, picaridin, oil of lemon eucalyptus, or other EPA-approved repellents to exposed skin or clothing, always following the manufacturer's directions for use. Download a brochure about selecting insect repellent from the Centers for Disease Control.