YANKEE DISTRICT OF THE AMERICAN ROSE SOCIETY

 


Win the Battle Against Rose Midge and Spider Mites With Prevention

By Tony Silva
 

Both rose midge and spider mites are microscopic in size and difficult to recognize until you see the telltale damage they have caused. They both reproduce very rapidly, causing a major infestation that will be difficult to control.

Iíll discuss rose midge first because it is the first to infest your rose garden in late spring or early summer. The tiny mosquito-like flies (about 1/20 of an inch) swarm into a rose bed when the rose bush sends out its first shoots. The tender tip, where you expect to see a flower bud develop, is the most susceptible area where the fly feeds. You will see a brown, shriveled bud instead of an emerging green flower bud. Forget any specimen bloom for the spring rose show from that stem.

I first noticed this problem on two plants in a corner of our garden about five years ago. Manny Mendes introduced me to the rose midge and the importance of cutting off the infested shoots and disposing of them. I inspected the rest of the garden that year and noticed no further infestations.

After two or three years of a rose midge problem, with an ever-advancing infestation on other plants in succeeding years, I realized that waiting for the evidence of infestation to become apparent before taking corrective action was too late; I decided that preventive and timely action was the only answer.

After all the care involved in getting a rose garden ready for the June blooms, it was utterly disheartening to see many brown, shriveled shoots on many of our rose plants instead of seeing developing rose blooms. I was ready to open the gate to our hybrid tea rose garden and let the deer in for a feast on the tender new shoots - a favorite feed for deer.

Last year I took the preventive approach. During the second week of May, I spread Diazinon granules lightly over the rose beds and the lawn between the beds, with a rubber-gloved hand. I followed this a day or two later with an Orthene (systemic) solution spray of the plants and the lawn. I repeated this the first week of July.

Last year I was unable to detect any midge problem on any plant until July 28th, and interestingly, on the same two plants of the first infestation five years earlier. I guess I missed some midge eggs and 1arve during my two treatments.

I consider my experience a success since all the writers on rose midge say that once you have rose midge in your garden, you rarely are able to eradicate it in future years. Preventive action rather than reaction is the answer.

The second feared pests in our rose garden are spider mites. In my discussions with fellow rosarians, Iíve found that there arenít many who have not experienced frustrating battles with spider mites. They are not truly insects, but are commonly included in that category of pests.

Like rose midge, they are microscopic in size and difficult to see with the naked eye. If you ever see me in the rose garden acting like a Scotland Yard inspector with a magnifying glass in hand, you will know that Iím looking for those tiny invading pests. When I see the lower leaves on a rose plant turning a bronze color and falling off, I bring out the magnifying glass and inspect the under side of the suspect leaf, or I might strike the leaf, upside down, on a piece of white paper. If I see colonies of tiny brown spots on the white paper, I know that I have an infestation of spider mites.

Spider mites are prevalent in hot, dry weather and multiply very rapidly. A serious infestation will cause serious or total defoliation of a rose plant. My miticide of choice is Avid (1/4 teaspoon per gallon), with three drops of Stirrup-M. I also add Indicate 5 as a spreader. You must repeat the spraying within four or five days to knock out the next generation of mites.

Tired of seeing spider mites causing defoliation of our rose plants, last year I was determined to prevent, rather than fight, infestations. Beginning the first week of July, I started spraying the under sides of the leaves with water, weekly, using a curved water wand. On very hot and dry days in July and August, I sprayed twice weekly. Last year I didnít see a single spider mite in our garden. My experience in the prior years was so frustrating, that I actually enjoyed the water wand routine.

As in the case with rose midge, preventive and timely action was the answer.

 

(Reprinted from Rhode Island Rose Review May 2003)

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