March 10, 2007
March is an important time of the year to do preventative work in your garden. Once the temperatures reach 40 degrees, you can do something to cut back on the number of insects and fungus diseases that invade your garden once the weather really warms up in the spring.
Insects do over winter on plant debris and on the stems and branches of many woody plants. In some cases, it is the actual insect that snuggles down for a long winters’ nap. In other cases, eggs are laid in the fall and as the weather warms in the spring, the eggs hatch out into new infestations of insects that will attack your plants. You can kill many of the eggs and the over wintering insects if you spray a horticultural oil on the woody plants in your garden. Horticultural oil comes either as a ready to spray product or as a concentrate that you can mix with water and spray onto your plants. As I said earlier, temperatures need to be above 40 degrees when you apply this product. Warmer temperatures allows the oil to flow into all those hiding spots where insects spend the winter. Once the oil covers the insects, they die. Eggs that are covered with the oil will also die. By cutting back on the number of eggs and over wintering insects, you will have fewer insect problems during the spring and summer. Certain plants really do need to be sprayed with horticultural oil. Rose bushes, fruit trees and any of the flowering trees that would be related to fruit. Think crabapple, plum and pear. This spray needs to be applied before new growth begins to emerge on the plants.
As many of you know, fungus diseases have been a problem the last few seasons. In the fall, fungus diseases form spores. Think of spores as eggs. These eggs over winter on plants and then when conditions are right, the eggs “hatch” and the fungus diseases are off and running. If you could kill the over wintering spores, then you could cut down on the amount of fungus diseases you would get on your plants. Rose bushes are one of those plants that are prone to many fungus diseases. Rose bushes get black spot, powdery mildew and a host of other diseases. The way to control the spores is to spray the rose bushes with a lime – sulfur spray. This spray is put on before the new growth begins in the spring. As with the horticultural oil, temperatures need to be above 40 degrees for the spray to properly work on the spores. Lilacs, fruit trees and crabapple trees also benefit from an application of lime – sulfur spray.
If you can get outside early and apply horticultural oil and /or lime – sulfur spray before the plants begin to put out new growth, then you can prevent a whole host of problems in your gardens.
Well, that’s all for this week. I’ll talk to you again next week.