This week brought the arrival our first guest teacher, Vic Izzo. Vic, an evolutionary ecologist, offered a new framework for pest management that begins with careful observation.
Evaluating whether or not a pest poses a threat is the second step in Vic’s framework. It is not always clear what presence and/or damage is within the tolerance of a given plant. The flea beetle, for example, will leave brassica leaves covered in tiny holes but cause no damage beyond the cosmetic imperfection.
On the flip side, there are some pests (known as nectar-robbers) that can show up and appear to be causing no damage at all. While they may not be affecting the plant’s appearance now, they can use their sucking mouth parts to extract pollen from the plant, which, in turn, will cause the plant to be passed over by important pollinators. Without pollination there will be no fruit.
As a beginning gardener, the identification of pests, along with the determination of their harmful or non-harmful nature, requires a dependable resource. This is true of long-time gardeners gardening in a new region too. At the Community Teaching Garden we use two:
A pest that has been successfully identified and determined to be a threat to the overall health of the crop can be managed in several different ways. In this third stage (management), Vic offered the Integrated Pest Management pyramid as a structure for decision-making.
Vic’s focus for the summer is on the leek moth. The leek moth is a pest of Allium crops with a hierarchy of dietary preference: leek, onion, garlic. We have no leek plants and only a few onions interspersed throughout the brassica sections of our garden. We do have a big and mature garlic bed right there in the center and, sure enough, Vic was able to point to the significant leek moth damage on the scapes of our garlic crop.
Pest identified and determined to be a threat to the crop. What to do next?
Choosing not to plant leeks, onions, and garlic could prevent the arrival of the leek moth. Too late! Cultural management often involves the strategic shifting of the physical location of a plant. Because the leek moths can fly, the garlic would not be helped by a move. In the case of the leek moth, intervening on the physical level is the best bet and, because the moths were feeding only on the garlic scapes, we decided that it was time for a harvest!