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The Rural Voice, 1998-11, Page 34Gardening The organic approach to debugging By Rhea Hamilton -Seeger Last month I wrote about problems in the garden. Damage in our gardens can be caused by insects, diseases, mammals and abiotic injury. We are going to focus on disease and insects. It is most difficult for even a professional to diagnose a problem based on the brief descriptions you find in books or on the backs of spray cans. If you are having problems then seek out a reliable book with colour pictures of the diseased plants. Take the time to read a bit about the agents behind the diseases — viruses, bacteria, fungi and nematodes. Viral diseases are spread via insects, like aphids, or by contaminated tools. Two basic groups are visible to the human eye. The mosaic virus causes the leaves to become mottled with yellow and green spots caused by the death of green chlorophyll cells in the leaves. Since chlorophyll feeds the plant through photosynthesis, their death leads to poor yields and stunted growth. The second group also causes yellowing as well as leaf curling, dwarfing or heavy branching. The curling or yellowing blocks the circulation system of the plant. The sad result is that with either disease you are probably better to dig up the infected plant and burn it. Bacterial diseases are caused by bacteria which are minute plants that feed off of others. They gain entry into a plant through a wound or a natural opening and use the sap to travel through the plant. Fortunately they are easily diagnosed by their symptoms. Rots attack leaves, stems and branches as well as tubers. The cell walls dissolve and become gooey, slimy, stinky messes. The second group of bacteria causes wilting. You will have seen its results if you have had black rot of cabbage or tomato canker. The third group is identified by galls or overgrowth of plant cells. These are not harmful until the galls grow so Targe they affect the flow of food and water through the plant. There is no real cure for this problem but you can make it difficult for bacteria to survive. Bacterial diseases enjoy wet soil, high humidity and high temperatures. If your plants 30 THE RURAL VOICE are pushed into a heavy growth spurt with heavy nitrogen applications it encourages wilt pathogens, so make sure your plants have nutrition in the form of compost or mulch. You can use disease resistant seed and make sure to rotate vegetable crops. If you spot a plant in your garden suffering from wilt disease, destroy it immediately to stop contamination of the rest of your crop. Fungi, like bacteria, get their energy from other plants. If it is from a dead plant then they are hastening the decomposition process and that is a good thing. If they are living off a living plant then you have a problem. Like bacteria, fungus is named after its symptoms. Downy mildew grows within the plant's cells and what we see is its branches spreading out to the surface of the plant cell. Powdery mildew lives on the surface and sucks oust plant juices via little tubes. Rust fungi colour the plant similar to the same damage that weather or spray injury could cause. The good news is that there are a number of sprays on the market but if you keep a clean garden and clean up any diseased plants you can fight and win this battle. Nematode diseases are caused by worm parasites that stick their heads into the plant and suck out the juices. Rotate your crops, use pest free stock and keep your plants healthy by enriching the soil with humus. Next come the insects. Insects and diseases are natural agents that aid plant selection. They don't head for the healthiest but the weakest. So your best ammunition is to help your plants be the healthiest they can be. You know the drill: soil high in organic matter, water when necessary and proper Tight. Insects are easy to combat once you identify them. You can make life miserable by planting companion plants together, rotating your crops, planting varieties resistant to a particular insect infestation and in perennial garden try repellent planting. To repel aphids try penny royal, garlic, chives or other alliums, nasturtium and petunias. Spearmint and tansy are also options but will quite quickly spread throughout your garden creating another problem. Nasturtium and marigold are also great repellents for whitefly. This is only part of a much longer list well worth seeking out. There are also biological controls where aggressive benign insects are introduced to eat, devour or create havoc among the destructive insects in your garden. The most popular ones are lady bugs and praying mantis. We are fortunate in having both in our garden and we try to avoid any and everything that might disrupt their stay. If you can identify your insect problem you can research out their life cycle and plot out how to disrupt it. Notice when they appear, and when they finish. You don't need a chemical here, just a bit of common sense. If your unwanted guests have a soil -borne stage you can disrupt them with scuffling; put off their cycle by planting long after the insects need your crop; spray water on the plants and repeatedly wash them off and literally dampen their spirit. If you know a particular insect overwinters in debris around your garden, clean it up and mulch with another product. I realize this is an uncomfortably short condensation of very valuable information so I encourage you to seek out a few very good books. The first is Organic Plant Protection by Rodale Press, those wonderful organic people in Emmaus, Pennsylvania. A heavy volume, it has a lot of in-depth information and yet even the most • inexperienced gardener can wade in and learn. The second publication is produced by our own Ministry of Agriculture, Food and Rural Affairs. Simply called The Gardener's Handbook, an Integrated Approach to Insect and Disease Control, it has been revamped and is more reader friendly than some of their previous publications. Good luck with your new diagnostic challenges. As for me I am going to continue to research until I find the name for the green worm that eats my roses all summer long and apparently does not stop until the frost hits. Most disturbing.0 Rhea Hamilton -Seeger and her husband raise two children at their home near Auburn. She is a skilled cook and gardener.