I got this email. It was all about buggies & stuff. Pretty neat read for a beginner like me!
Powdery Mildew
In the cool damp nights of early spring here in Oklahoma the conditions are right for the growth of powdery mildew. It typically only shows up on some varieties of roses and those same ones will be the ones who show it every time the weather is right. Warm weather will stop it but in the meantime you should spray with Jojoba Oil which is the active ingredient in Erase. It may take a few applications 3 days apart to get rid of it if the weather doesn't warm.
Cucumber Beetle
These critters come early to the garden and stay late. Unlike the aphids and mites they are chewing insects and can make a rose look awful in a very short time. Look for them under the leaves and especially down in the bloom. Malathion are carbayl (sevin) will control them quickly and if used as a spray late in the evening they will do little to hurt beneficials.
Thrip
These little suckers like the Aphid take nutrients from the roses. Unlike the Aphid they have a rasping mouth part that splits the cuticle and allows them to dine on the roses nutrients. Flowers not opening is one of the tell tale signs of Thrip infestation. If you suspect Thrip on your roses just take a piece of white paper and shake the suspect bloom over it. If the Thrip is present they will fall onto the paper and you can see them scurry away. Acephate (while it is still available) is a very effective pesticide for Thrip because it goes systemic and the Thrip die when they ingest it. Malathion is also effective against Thrip but it is difficult to spray it down into the blooms to the are the Thrip are feeding.
Spider Mite
Another little sucker that causes real devastation to the affected bush and left unchecked will kill most roses over time. The signs to look for are a dirty appearance on the under side of the leaves. If your eyes are good you may actually be able to see them moving around and in bad infestations the webs that they build. Under a magnifying glass you can see the mites and their eggs. Malathion will kill adult mites but because it doesn't kill the eggs you will have to spray at 3 day intervals for 9 days. If you miss a day by even one day the spray cycle must be started over again. Mites generally wait until warm weather to become a problem but I have already been finding some in full sun locations. Once it gets hot outside the mites can progress from egg to a laying adult in just 3 days. Hence the spray cycle. Because of the difficulty encountered in controlling mites I would highly recommend a miticide/ovicide that we carry here at Roses inc. called TETRA San. Spray it once and it kills eggs and prevents the adults from reproducing. A couple of days after you use it the nymphs will be dead and the eggs will be black indicating they are no longer viable. The adults may still be present but they are not feeding or reproducing and will die soon.
Black Spot
Leaf spots are caused by a fungus and several fungus that attack our roses are lumped into the category of Black Spot. Black Spot needs 80% humidity and temperatures between 65 and 80 to grow the best. That kind of sounds like Oklahoma doesn't it. The trick to not losing leaves to black spot is two start a preventative spray program a week after pruning and continuing it until the first killing frost. Spray at least once a month. Many people belive that they must just live with Black Spot on their rose bushes but that is not correct. If you use the right product and follow the spraying instructions you can have few if any black spotted leaves. The trick is to be consistent in the use of your fungal spray and use a fungal spray that works. For the spray to be effective it must have two modes of action to deal with the fungus. Roses inc. Black Spot remedy is the only package I am aware of that meets this criteria. It is easy, safe and quick to use. Call or stop by for more information on the prevention of Black Spot
