Midsummer Tips for Pest & Disease Control

It’s the height of summer and gardens everywhere are bursting with life. With that comes some of the biggest challenges gardeners face: pests and diseases. To help you keep your garden in shape, here are some bite-sized tips for staying on top of it all.

Flowers in the garden attract beneficial insects. The small flowers of herbs and greens that have bolted are especially attractive to certain beneficials like hover flies. These blooms also make beautiful cut flower arrangements!

Flowers in the garden attract beneficial insects. The small flowers of herbs and greens that have bolted are especially attractive to certain beneficials like hover flies. These blooms also make beautiful cut flower arrangements!

1) Weed. Weeds not only compete with your plants for water and nutrients - they also harbor and spread pests and diseases. So clear them out! If they are visibly infected, or are already producing seeds, put them in the trash rather than the compost pile. 

2) Mulch. Use straw, grass clippings (without weed seeds or chemical treatments), pine needles, torn newspaper, or coco mulch to cover all garden soil. Mulching surpresses weeds, conserves moisture, and prevents soil-born diseases from splashing up with the dirt when it rains. For these reasons, a good gardener follows the mantra “no bare soil!”

4) Water wisely. Take care to water at the right time, and in the right amounts, to keep your garden thriving and disease-free. If watering from above, only water in the morning. This allows the foliage to dry before the hot midday sun, which can cause damage to wet leaves. Watering in the evening is unwise because cooler evening temperatures plus damp conditions make plants more vulnerable to disease. Last, but not least, give your garden a deep watering of 1-2” once per week - that’s it. Over-watering stunts plant growth and creates favorable conditions for disease. You can put out a container to measure the amount of water your garden is getting. Rainfall counts toward the total 1-2”/week requirement, and after a rainfall is actually an excellent time to water if your garden still needs “topping off.”

3) Remove dead and diseased material. Prune off dead or diseased leaves with a clean scissors or clippers. Sanitize tools with rubbing alcohol and wash hands between plants. If a plant is badly infested, part with it completely - pull it up and put the whole thing in the trash, along with any other affected material.

3) Allow air flow. A lush garden is fun, but too much crowding reduces air flow, which in turn allows diseases and pests to thrive. Go through your garden and do an inventory - do you have an abundance of volunteer tomatoes that you have let stay “just to see” if they’ll produce anything? Have your squash or cucumber vines invaded another crop? Perhaps it’s better to clean out those volunteers and head off the crazy squash vine with a clean snip rather than risk the health of your garden. Another helpful thing you can do: go through with a clean scissors or pruners and clip away all the lower leaves of your tomato plants. These are the first to get diseased and aren’t needed once the plant is large and has plenty of foliage higher up. Better to clean things up.

4) Remove pests. Not only do pests eat your crops - they also spread disease. Removing pests by hand is the best course of action in the garden. Pesticides and other control methods, even “natural” ones (like diatomaceous earth and bug traps) kill the good bugs along with the bad, which can further upset the balance in your garden. (If you have a Dynotrap, better not use it near the garden!) So, put on your big boy/girl pants, and flick or pick pests off of your plants and into a bowl of soapy water. The morning is the best time to do this, as bugs are typically more sluggish. Not sure which bugs are bad? I have a few pictures below - otherwise the internet is your friend!

5) Encourage beneficials. Not all bugs are bad! Some are extremely beneficial in controlling pests in the garden. You are probably familiar with ladybugs, lacewings, and dragonflies. See below for a couple pictures of hover flies, another excellent ally in the garden. You can encourage beneficials to move in by planting flowers and herbs, and letting herbs and greens flower rather than pulling them out (this provides tons of tiny flowers that many beneficials love).

6) Take notes for next year. Finally, take note of where you planted everything so you can rotate your crops next year. For example, this year I had an infestation of tarnished plant bugs on cucumbers I grew against the fence of my neighbor’s weedy yard. The bugs spread to nearby squash plants. From now on, I will not plant against that fence because of the weeds, but I will also move my squash and cucumbers to a different location next year to avoid re-infestation.

I hope these tips inspire you to get out there and get your garden in order for a strong finish! See below for buggy pics.

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Hover Flies

Hover flies are colored like wasps but have the head of a fly. They love small flowers and are one of the most beneficial bugs to have in the garden!

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Hover Fly Larvae

The larvae of hoverflies are small green or brown maggots, and they eat a TON of bad bugs in the garden, especially aphids.

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Japanese Beetles

The bug we all know, and hate: the Japanese beetle. These will skeletonize leaves, and worse, eat fruit. Stay diligent in picking these off, because once they start feeding on a plant, they signal others to join them via pheromones.

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Squash Bugs

Squash bugs are a BAD BUG. They will decimate your squash, cucumber and melon crops. They lay groups of brown eggs in the center of leaves. Pick off both the bugs and the eggs to control populations.

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Cucumber Beetles

Cucumber beetles are another pest. They feed on leaves and flowers of squash and cucumber plants, which can damage the plant and reduce yields, plus spread disease. Tap them into your bowl, or catch them with petroleum jelly-coated yellow gloves!

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Tarnished Plant Bugs

Tarnished plant bugs are tiny, hoppy little things. They almost look like miniature crickets. They suck the fluid out of the leaves, leaving a dappled appearance. This inhibits the plant’s ability to photosynthesize and will stunt growth or destroy the plant.

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Ants

Are ants in the garden good or bad? Trick question - they can be both. They eat eggs and small pests, but are also known to actually tend to aphid colonies so they can eat the sweet, sticky substance they excrete (called honeydew). Don’t worry about their presence, but rather keep hand-picking other pests and encourage beneficial insects!