By Lauren McDonald
Our fundamental approach to combatting pest pressure is to grow healthy plants from the beginning of their life cycles in the greenhouse until harvest in the field. This means using high quality potting soil and careful watering practices in the greenhouse, optimizing weed management so the plants are not stressed and competing for resources, planning and protecting soil health, and carefully monitoring irrigation and water needs. In short, the combination and interaction of all the farm systems you’ve been reading about in these newsletters results in plants that can resist damage from insects and diseases.
Additionally we use physical barriers to protect our crops from insects. We cover most of our Brassica crops (broccoli, kale, collards, cabbage, arugula, bok choi etc) with Reemay floating row covers- these are the big white covers you’ve probably seen on the farm. This polyester-like fabric keeps out the small black flea beetles that eat pin holes in leaves and can destroy tiny seedlings. We also cover all cucurbits (cucumbers, squash, and melons) until they start flowering in order to block out the cucumber beetles that suck fluids out of leaves and stalks and spread bacterial wilt disease. The row covers also protect from cold in the spring and fall- each layer of Reemay can add about 5° of warmth, depending on the weight of the cover. Another physical barrier system you’ve probably seen on the farm is our blueberry netting to keep birds from eating berries. We installed new netting curtains for the blueberries in July.
We also make specific decisions about timing and planting location in order to manage pest pressure. We transplant snap peas because when they are seeded directly in the soil, seedcorn maggots (or possibly earth worms) tend to eat the seeds. Similarly, we time our last planting of cucumbers and zucchini so that we’ll finish harvesting from the plants by early September when downy and powdery mildew will start to come in. For the whole farm, we use a four-year crop rotation meaning that a particular crop family will only be planted in each section once every four years. This helps avoid diseases and insects that stay in the soil.
High tunnels are also valuable ways to manage disease in tomato and cucumber crops and a significant reason for installing the two new ones this season. When tomatoes are grown inside a plastic tunnel, rainwater and dew doesn’t settle and sit on the leaves the way it does in the field, consequently minimizing the spread of water-borne diseases. In the past, we sprayed a copper soap on tomatoes and peppers. The copper reacts with water and becomes toxic to the disease causing fungi. Instead, having all our tomatoes under cover will potentially eliminate or at least significantly reduce our copper spraying. With insect pests we do also use organically approved chemical sprays as a last resort, and we try to avoid spraying the same chemical more than once on the same crop/pest. All of these pest management techniques require us to be constantly observant and to closely monitor every crop. So, if you’re ever picking in the field or working with us and notice an unusual insect or potential disease, please let us know!