August Gardening – Insect and Disease Control

    Published: 06-16-2009
    Views: 12,604
    Mitch Baker with American Plant talks about insect and disease problems in the garden.

    Mitch Baker: Hi! I'm Mitch Baker with American Plant. Let's talk about insect and disease problems in the garden. Nothing is worse than spending hours and hours in the garden only to have it damaged by insect and diseases. So, to control infestations in your garden, make sure you follow these simple tips.

    Learn to identify a small problem before it becomes a big problem, and here is an example of a dogwood. We have three distinct disease problems going on here all at the same time. Powdery mildew is this white powdery substance on the leaf surface and that's fairly easy to spot, it's also fairly easy to control. The other two problems are a little more complex, Discula Anthracnose and Leaf Spot Anthracnose that both cause this cupping, curling and distortion of the leaves.

    That's something that carries over from season to season, and eventually causes a reduction in the amount of new growth, a reduction in the leaf size. We start to get some dieback within the interior of the tree, and an overall lack of vigor. Now, Discula Anthracnose, if it progresses, if it goes on long enough, that's considered a terminal problem.

    Leaf Spot Anthracnose, just like powdery mildew is something that can be controlled if you begin spraying early in the season. But by late in the summer, by this time of year, all of these problems are much more difficult to control.

    Next, we're looking at a Cotoneaster that is suffering from Lace Bug. Lace bug is a small sucking insect that you'll find on the underside of the leaves, and that's what makes it difficult to identify, because you don't see the insect. But the damage is readily apparent. As a sucking insect, they're basically removing all of the chlorophyll from the leaves, and those dark green leaves turn very pale green, almost yellow or white, and that's a high-level infestation of lace bug, once it reaches that stage.

    On a Cotoneaster or any other low-growing plant like this, it can be difficult to spray to control that, because you have to get to spray under the leaves to come into contact with the lace bug.

    Now, here is a Cherry Laurel where we're seeing some damage from the Snowy Tree Cricket. This is a very reclusive, nocturnal cricket. You're not likely to see this critter, but you can certainly see the damage, the sort of rasping away of the upper surface of the leaf.

    Sometimes, you may not notice it for three or four weeks. That's about how long it takes for the leaf to brown off. Usually, not a high enough level of damage to threaten the health of Cherry Laurel, the damage is more cosmetic.

    These are just a few tips to help you identify unwanted insect and disease problems in your garden. If you should see any signs, contact your local garden center to learn how to control them early.