If I had it to do over again, I would do the amateur rose hobby a little differently. I would group the no-need-to-spray tough varieties together and group the black spot-susceptible ones together. That way I could be an organic gardener over here and a disease-preventing learned gardener over there. Actually, both methods require some learning. As for insects, I have only sprayed roses one time in the past seven or so years. Aphids moved in one spring and were big-time sucking the juice from all varieties, including the tough ones.
Some of the plants we grow or want somebody somewhere to grow so we can buy groceries come with inherent bug and disease problems. Some rarely have such problems. Just keep in mind even those normally pest-free plants can, might, or possibly have an unexpected intrusion by a damaging critter or microbe. The role of gardener or farmer is to be aware of the possibility and to make a decision whether some kind of action is called for.
Among the almost guaranteed pests in plants each year are scab disease in pecan trees, boring caterpillars in cannas, and both brown rot and curculio worms in peaches. Those pests are among the ones that require preventative measures. Waiting until damage symptoms appear is too late. Odds are they are going to be there every year and greatly reduce the yield of pecans or peaches and the good looks of cannas if no preventative measures are taken. In commercial food crop production, such prevention comes into play even for some disease pests that are not as absolute as annual occurrences. It is a risk-benefit scenario. Applying preventative fungicides is to offset the one-in-five chance of near total crop loss if a disease pathogen is left to, well, to chance.
Gardeners, for the most part, can usually wait to see insects or their damage before taking action. That is if gardeners are checking on their plants often. For plant diseases, many of those need a response at the very earliest sign. Remember, you can see a bug, but not a fungus or bacteria. Those ugly spots result from but are not the actual pathogens. They are very microscopic.
A lot of home gardeners handle pest problems by avoidance; they just don’t plant things known to have constant bug or disease challenges. And that is a pretty good way to garden. Or, plant two tomato plants each spring and insist that all other plants are low maintenance. Go with plants whose pest problems range from rare to none. Varieties of such plants are actually increasing in number and availability. Modern plant breeding and plant marketing puts a premium on varieties that customers can successfully raise without babying. The Knockout Rose, for instance, has made rose maintenance easier than lawn maintenance for sure and about as easy as growing monkey grass. The thing to know, though, is there are numerous other easy-grow roses, some from century before last on up to year before last. Look them up.
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Terry Rector writes for the Warren County Soil and Water Conservation District, 601-636-7679 ext. 3.