Beating the Heat
Dealing with the Pests and Drought of Summer
by: Aidan Feeney
Summer is here and the garden is in full swing. Tall tomato plants are loaded with fruit soon to ripen, cucumbers are weighing down their vines and your neighbors have probably learned to avoid you if they don’t want any more zucchini. Hot, lazy summer days are the stuff of gardening dreams.
As always though, nature has a way of keeping us on our toes. As temperatures rise and the ground dries out, new challenges present themselves in the garden. All those beautiful crops you grew in the spring might very well succumb to pest damage and water stress if you don’t put some forethought into your garden plans. Here are a few steps to keep the garden productive through the summer doldrums.
You can look at water as the most fundamental of all fertilizers. Just as with plant nutrients, your crops will suffer from too much or too little water. Without it, plants die very quickly. As a gardener, you should never allow your soil to completely dry out.
Plant roots need both air and water, and as such, an ideal environment for most plants is a moist but not fully saturated soil. This allows for the continued growth of your crops. That being said, some of us value our time more than others, and maybe you would rather be fishing or enjoying a cold beer at the beach instead of constantly hand watering your entire garden. Not to worry: there are solutions.
I believe that irrigation is essential for anyone who wants to grow food reliably. Simply put, irrigation allows you to germinate, grow and harvest crops on a regular schedule. Irrigation also improves the productivity and quality of your crops. Without regular watering, you’ll be eating bitter lettuce, your tomatoes will likely split and many fast-growing crops such as radish, fennel, bok choi, etc. will flower before reaching a harvestable size.
Irrigation for the garden can be very simple. You can run a drip line system and/or multiple mini-sprinklers all off of one garden hose with decent water pressure.
For beginners, I recommend setting up a system using drip lines. Drip irrigation is the preferred method for watering plants that are prone to foliar diseases, such as tomatoes, cucumbers, basil and peppers. Drip irrigation is great for watering transplanted and established crops, but its one shortfall is that it is not the best at germinating crops that are seeded directly into your garden’s soil. When direct-seeding crops, make sure you water them with a watering wand or a sprinkler until they are fully germinated and established.
Another less intuitive method for preventing water stress is adding compost and mulch. Compost raises the organic matter of your soil, which in turn allows it to hold on to more water. This is why a healthy, biologically-active soil will dry out much slower than a sandy, low-organic-matter soil. A wood-chip mulch has the same effect as compost, and also covers your soil and prevents direct sunlight and wind from drying it out. Even just a layer of woven landscape fabric will help your soil retain moisture and keep the soil temperatures lower.
Lettuce can be a very difficult crop to grow throughout the summer season. Keeping lettuce from bolting (going to flower and seed) and tasting bitter requires some effort in the summer months.
My first suggestion is growing a Batavia/Summer Crisp variety. These lettuces are relatively heat-tolerant and they taste great. My favorite varieties of this type are Muir and Nevada. Secondly, lettuce needs regular watering, preferably overhead watering from a wand or a sprinkler. This helps to cool the plant down, in addition to keeping it from going bitter.
Lastly, you might want to consider using shade cloth to help keep your lettuce and any other heat-averse crops growing well. Shade cloth is available in many densities, although for growing vegetables, I would not use anything more than a 50 percent shade. You can use a cold frame, EMT hoops, a greenhouse or any type of structure to suspend the shade cloth above your crops.
As summer progresses, we get a growing number of pest species that are likely to visit our gardens. Insects become active at specific temperatures, and as the ground and ambient temperatures rise in summer months, more and more pest species become active and act out their life cycles.
Remember that perfect-looking kale in May and June? Now it is a mess of hole-ridden leaves hanging on for survival. Remember that perfect-looking tomato you were waiting to ripen? Now it has a nice big hole in it and caterpillar-bite marks all over. There are preventative measures that can be taken to avoid losing your crops like this.
Know your enemy. The most important step in pest management is identifying what pest you are actually dealing with. What follows is a list of the most prolific pest species, detailing which crops they are likely to afflict and how to manage them.
• Tomato hornworm: This is a large green caterpillar with interesting white and black patterns on its side and what appears to be a horn on its back end. You will likely find holes in tomatoes, missing leaves and little piles of green scat on or at the base of your tomato plants when they are around.
You normally find them on tomatoes, although they will also eat eggplant, pepper and potato plants. The best method for controlling these is hand-picking, spraying Bt (Bacillus thuringiensis) or closing in your tomatoes at night. The caterpillar larvae is laid by a nocturnal moth, so if it is possible to keep your plants covered with row covers or closed in a greenhouse at night, they will not get hornworms.
• Cabbage worm: All of those pretty white moths you see flying in the early summer are actually the culprits killing your kale, broccoli and cabbage. They lay eggs that hatch into little green caterpillars that love to eat brassica crops (cabbage, kale, cauliflower, Brussels sprouts, broccoli, etc.) The best thing to do is cover these crops preemptively with row covers. This will prevent contact to begin with. If this is not possible and you encounter them, you can hand-pick or spray with Bt.
• Cucumber beetle: These are little flying beetles that love to eat your cucurbit crops. These crops include cucumber, melons, zucchini, winter squash, pumpkin, etc. They are either yellow with black stripes or they can be polka-dotted. They swarm plants in large numbers and like to hang out in plant blossoms.
They mostly feed on the flowers and undersides of the leaves, eventually transmitting bacterial wilt. The best intervention is a row cover. Perhaps spraying neem or PyGanic could be helpful, although it has never helped me.
• Flea beetle: These are little black beetles that spring from plant to plant. They become active early in the summer and they target young, tender crops. Different species of flea beetles prefer different crops, although the ones I deal with tend to go after my arugula and radishes. The only method of prevention is a row cover, or just planting outside of their season, which only runs June-August or so. ///
Aidan Feeney is the owner of Fog Town Farm on Hummock Pond Road and a regular contributor to Nantucket Today.