Vine Borer: When A Healthy Looking Zucchini Plant Suddenly Dies?
Zucchinis are one of the most popular vegetables in our country. They are very easy to grow and produce a large amount of delicious food. However, they have their own set of pests which can cause them to die prematurely or even kill them completely! One such pest is the vine borer (Osmia formosa). These little beetles feed on the leaves of your zucchini plants. Their main prey is the vines, but they will also eat other parts of the plant including roots. If left unchecked, these pests can destroy your zucchini crop within just a few years!
The vine borer has been around since ancient times when it was used to control wild grapevine populations. Since then, it has spread throughout Europe and North America. Unfortunately, it has become resistant to many common pesticides so you need to use special insecticides if you want to keep these pests under control. You may not realize that your zucchini plants are infested with vine borers until they start dying off all at once. This happens because the larvae burrow into the skin of the plant causing it to turn yellow and eventually die.
The adult vine borers are a dark metallic green with a shiny exoskeleton. They have chewing mouth parts and antennae. They grow to be about 1cm long and are typically active during the warmer parts of the day (such as early morning and late afternoon). During the winter months, they enter a state of semi-hibernation and can survive on just a small amount of food. They typically lay their eggs on the undersides of leaves.
The eggs are white and spherical in shape. The larvae that hatch from these eggs are tiny white worms that grow to about 1cm in length before pupating. During this time, they move to the soil below and tunnel into the ground to avoid being eaten by birds and other potential predators. Even after they develop into adults, the moths will avoid sunlight and remain underground until conditions above are favorable for them again. The entire cycle takes about three years to complete!
As you might be able to tell, these insects are very tricky to deal with. Many people attempt to control their vine borer populations by hand. You should try to do this early on before you see any zucchini plant wilting in the heat or yellowing. Look underneath the leaves for small white eggs and remove them. Use your fingers, a straightened paperclip, or another small tool.
Remember that the larvae are quite tiny so you may have to look carefully!
If you do not want to look for the eggs yourself, you can always use one of many available insecticides on the market. Organic gardeners can use neem oil or make their own garlic spray which is effective against many pests (including vine borers). Once you have applied your chemical or organic agent of choice, be sure to avoid the leaves since these chemicals can be harmful if absorbed by the plant!
Be warned that many over the counter pesticides are not very effective against vine borers. These insects have built up an immunity to many of the ingredients found in standard pesticides (such as organophosphates). Do not waste your money! Instead, spend it on some of the newer pesticides that have become available in recent years.
There are also some biological controls such as the wasp Parasties maculipennis. This tiny wasp lays its eggs inside the eggs of the vine borer. The wasp eggs hatch and the resulting grub devours the vine borer eggs. Unfortunately this parasite is not very effective since it can only attack the eggs and young larvae. There are also some nematode species (such as Steinernema scaptericum) that kill vine borers through infection.
Unfortunately, these can take up to three weeks to take effect and can be hard on the environment.
If all else fails, you’ll have to resort to chemical controls. Always follow the instructions on the label closely, and make sure to protect yourself with gloves, a mask, and eye protection. Remember that these chemicals are poisonous!
Remember, vine borers may seem like an overwhelming foe, but by keeping on top of them you can easily overcome their attack! Happy growing!
Sources & references used in this article:
Natural insect control: the ecological gardener’s guide to foiling pests by W Schultz – 1994 – books.google.com
A guide to the clearwing borers (Sesiidae) of the north central United States by L Nancarrow, JH Taylor – 2000 – Random House Digital, Inc.
The organic gardener’s handbook of natural pest and disease control: a complete guide to maintaining a healthy garden and yard the Earth-friendly way by WH Taft, D Smitley, JW Snow – 1991 – conservancy.umn.edu