Flea Beetle

Flea beetles are most active in spring when adults emerge and their feeding can severely damage seedling plants. Hot-pepper spray can be effective. Commercial pepper sprays are available for purchase also; the active ingredient should be capsaicin.

Neem oil and some horticultural oils are effective at repelling flea beetles, these can be purchased from Home Depot and garden centers.

Jumping Worms

Photo courtesy of University of Illinois

Some earthworms are beneficial to gardeners through soil aeration (earthworms) or composting (red wigglers). However there is a growing problem with a new invasive species (Amynthas spp) that is particularly destructive to soil structure and soil chemistry.  Commonly called invasive jumping worms, crazy worms or snake worms (previously referred to as Asian jumping worms), they are both extremely fast spreading and destructive. They can drastically reduce the productivity of your plot , particularly with plants that are not established by mid June.

Good garden hygiene is the best way to avoid the introduction of this species. This means either isolating your tools to your bed only, or washing tools between use on different beds. Never bring an unwashed tool from home to the garden, or transplant soil from elsewhere. Try to check that bagged soil products introduced to plots are marked as “sterile”. This can be difficult, though, because companies are slow to recognize the issue. 


How do you know if you have jumping worms? Testing the soil can only be done effectively after spring eggs hatch, and grow to a size that's easily seen, probably in mid-June:


Mix ⅓ cup of ground hot yellow mustard seed (look for Chinese or Asian hot mustard) into 1 gallon of water and pour half of the liquid slowly over a 1 square foot of soil you want to test. Wait a few minutes and pour the rest. This will make worms (any earthworms) come to the surface.

Once the worms are big enough to see on soil surface, you can hand pick them to reduce numbers. Place  the worms in a jar or bucket with a mixture of 2/3 water and 1/3 vinegar or rubbing alcohol. They die quickly. They can climb out of buckets of water, so you need to kill them. Don't dispose of eggs or live worms down drains or toilets, as they will get into rivers and spread.

Check the Resources page for links to more detail about current research, prevention and mitigation measures.



Powdery Mildew

Powdery mildew affects squash plants, spreads rapidly, and will travel all over the garden. In addition to squash plants, it will afflict any number of veggies, including: artichokes, cucumbers, eggplant, lettuce, melons, parsnips, pumpkins, and gourds So if you discover powdery mildew on your squash, keep an eye on other plants in the same family, cucurbits, and start treating them straight away. Disinfect any tools after working around cucurbits. If you use a tool around summer squash, for instance, disinfect the tool before working around cucumbers. If the tool isn’t disinfected properly the powdery mildew spores will be passed from one plant to the other. Disinfect tools with full strength vinegar or a solution of one part bleach to nine parts water.


Powdery mildew thrives in moist conditions so allowing the leaves to remain damp overnight can increase the likelihood of powdery mildew. It is better to water the soil around the plants and avoid getting the leaves wet.

You will need to prune the leaves that are heavily infected and remove the debris from the garden. Please remember to bring your own bag or use one of the take home trash bags, ( found on the shed door or attached to one of the compost bins). Please do not place diseased vegetation in the compost bins.


To successfully kill powdery mildew on the leaves, you need to act at the earliest sign of infection.  One of the best organic treatments is a solution of milk and water sprayed on the leaves.

Early Blight

Early blight is a fungal disease of tomato plants that shows up as spots, usually beginning on leaves of the lowest branches, which then turn yellow and die. 

These are the best practices for preventing and treating early blight:

This article will help you to identify early blight.

Striped Cucumber Beetle

The striped cucumber beetle is one of the most devastating pests of cucumbers, all types of squashes, all types of melons, and pumpkins. Both adults and larvae feed on these crops. This insect is also responsible for the spread of plant diseases, such as bacterial wilt and squash mosaic virus. You can treat a striped cucumber beetle infestation in the same way as for flea beetles - Neem oil and pepper sprays.

Colorado Potato Beetle

Although they are mainly a pest of potato plants, these beetles also lay waste to other members of the hemlock family, such as peppers and eggplant. The beetles start laying larvae as the weather warms. If you are growing eggplant, the potato bug larvae will be gray. As they get larger, you will notice the larvae beginning to sport black dots on their sides. If you see larvae or adult beetles, remove them and drop them in the soapy water. Doing this every day will greatly reduce the number of potato beetles in your garden. Using an insecticidal soap spray is also a good way to control these bugs.

Japanese Beetle

In summer, adult Japanese beetles hatch and emerge from the soil to start feeding. They are voracious eaters, not choosy, and have no natural predators.  They are easy to identify and to hand pick.  Keep a container of soapy water handy when you go hunting. When you grab one, throw it in the soapy water, or just squish them. We put traps out on fences to lure them away from the garden plots but that is only partially successful so it pays to pay attention to your own plot. You can read more about Japanese beetles here.

Tomato Hornworm

These large green caterpillars can quickly destroy your tomato plants, eating both leaves and fruit. They are hard to spot because they blend into the foliage, so look for eaten leaves and the caterpillar’s dark green droppings. Remove from the plant and use your feet to squash them (or drop them into soapy water). However if you see small rice-like grains on the back of a caterpillar, leave it alone. The grains are the cocoons of larvae of a braconid wasp that laid its eggs inside the caterpillar. When the adult wasps emerge from the cocoons, they kill the hornworm and look for other hornworms to prey on. You can read more about tomato hornworms here.

Photo by Yolanda Miller.

Squash Bug

The squash bug is a pest of squash and pumpkin plants and can cause young plants to wilt and die. The female lays clusters of orange eggs on the underside of leaves. These hatch first into light grey nymphs and finally into mature bugs. The best strategy is to regularly inspect the underside of the leaves of your plants for eggs and then remove and crush the eggs.  Nymphs and adults can be killed by dropping into soapy water. For more details, read these articles:



Basil Downy Mildew

Basil downy mildew infected the garden at High Plain this year and destroyed most of the basil crop. At the onset of the infection, lower leaves of the plant start turning yellow, then turn brown and curl up. The back of the leaves become  covered with a black dust. Eventually this spreads to the whole plant. Unfortunately there is no known remedy and we recommend you uproot infected plants to put in your garbage at home. 

The disease mainly affects green-leafed varieties of sweet basil; purple-leafed varieties of basil, Thai basil, lemon basil, and spice basil are less susceptible.  The College of Agriculture and Life Sciences at Cornell University has a comprehensive description of the disease and up-to-date coverage of the development of disease resistant varieties. Here is advice for avoiding Basil Downy Mildew when planting. Look for the Prospera varieties available from Johnny's Seeds, which are downy mildew resistant.

Good Bugs

Tiger Beetle

A tiger beetle eats an array of insects.  Some have small mandibles and can only eat really small insects, and some have large mandibles that can only eat larger insects. This means that several tiger beetle species with different-sized mandibles can live together in the same habitat because they don't eat each other's food. The beetles construct tunnels in the ground and wait just below the surface for prey to pass by. When they sense something close to the entrance, their head snaps upward like a miniature steel-jawed trap and drags the helpless prey into the tunnel to be eaten. 

Photo by Deb.

Braconid Wasp

These are small wasps with narrow waists and long antennae, usually less than ½ inch long, with a long black ovipositor extending from their rear ends.  The adults use the ovipositor to lay eggs in caterpillar pests, such as cabbage worms and tomato hornworms. The larvae feed inside their living hosts, weakening or killing them.  If you see a caterpillar with cocoons like grains of rice on its skin, you should allow the larvae to hatch to generate the next generation of wasps.

Photo: Richard Bartz  under the Creative Commons Attribution-Share Alike 2.5 Generic license.


Adult lacewings feed on nectar and pollen. Their offspring are not so pretty and look like leather-armored slugs. The larvae are voracious predators and feed on aphids and soft-bodied caterpillars.

Photo: Donald Holbern under a Creative Commons-BY 2.0 license.