Pests and Diseases

Pests and diseases can have a far-reaching effect on vegetable crops. For the home gardener, they can be an inconvenience, but for commercial vegetable producers, they can be catastrophic.

Make use of Penn State Extension’s comprehensive library of resources including recommendations for managing pests and diseases for vegetables such as tomatoes, potatoes, onions, asparagus, squash, peppers, and many more. Find tips on dealing with worms, maggots, leaf miners, beetles, and mites, and scouting for pests. Penn State Extension also regularly publishes PestWatch Reports and Pennsylvania Vegetable Disease Updates in this section.

Common Vegetable Diseases

Vegetable diseases take their energy from the plants on which they thrive. Much the same as pests, diseases can be responsible for a great deal of damage. Wet weather, poor drainage, or inadequate airflow often encourages them. A variety of symptoms, including moldy coatings, wilting, blotches, scabs, rusts, and rot typically characterize plant diseases.

There are several common vegetable diseases that growers should be aware of. Timber rot, also known as Sclerotinia or white mold, can be a problem if air circulation and moisture retention are poor. Leaf mold can cause problems when you grow tomatoes in high tunnels. Early blight, caused by the fungus Alternaria solani, is a common problem for potato growers, particularly in warm weather regions that alternate between dry and wet.

There are distinct symptoms you can look for if you want to identify vegetable diseases. Penn State Extension’s Identifying Potato Diseases in Pennsylvania publication contains color photos to help determine what diseases are affecting your potato crops.

Preventative plant disease management tactics are the best approach to manage diseases. Basic principles include avoidance, exclusion, use of resistant varieties, accurate pathogen diagnosis, and pathogen reduction. Plant analysis plays a crucial role in determining what is wrong with your crops.

Scouting should be used to monitor your fields for the presence of diseases and pests or any potential issues that could hamper the growth of your vegetable crop. If your cucurbit crops are wilting, it could be cucurbit yellow vine decline, Fusarium, or bacterial wilt that is causing the problem.

Vegetable Garden Pests

Various insects and pests can damage vegetables in the garden and they can attack at all growth stages. The spotted lanternfly is an invasive insect that has been spreading throughout Pennsylvania for several years now.

Let’s not forget there are also lots of beneficial insects you can find in and around vegetable crops. Common natural enemies in high tunnels include green lacewings, lady beetles, and parasitoid wasps, all of which enjoy feasting on aphids, scales, and mites.

If you find white meandering tunnels in your chard, beet, or spinach leaves, your vegetables may be falling victim to leaf miners. The legless yellow to white larvae cause damage when they burrow between the layers of the leaves as they feed. Onion, seed corn, and cabbage maggots attack seeds and small seedlings.

Tomato hornworms can be a problem for tomato plants from July through early September in Pennsylvania. A single lime green, small shiny egg on the top or bottom surface of leaves of not only tomatoes but pepper and other solanaceous crops indicates their presence. Broad mites are another pest that can cause severe damage to peppers and tomatoes. You can protect your crops with an effective miticide.

Vegetable Crops and Integrated Pest Management

Integrated pest management (IPM) is a way you can manage insects, diseases, weeds, animals, and other pests that cause damage. It involves a combination of biological, cultural, mechanical, and chemical practices. You can apply the principles of IPM to both commercial and home vegetable growing. The key to applying integrated pest management is scouting for pests and diseases in vegetable crops.

Biological practices include releasing insects and mites along with bio-pesticides composed of specialized fungi and bacteria. Insect pheromone traps can also be used to help control insect pests such as black cutworm. Heat treatment of the soil is another practice that has a place in an integrated pest management system.

Vegetable Pesticide Application

There are several effective ways to deal with pests. If you want to use pesticides on your vegetable crops, you may need a license. You must fulfill a continuing education requirement if you want to maintain a valid private pesticide applicator license in Pennsylvania.

Penn State Extension provides a number of workshops for anyone who is looking to become certified or recertified. The courses available include the Private Pesticide Applicator Short Course in Spanish and English. A pesticide spray record-keeping spreadsheet is also available.

If you want to take the guesswork out of spraying there are smartphone and tablet apps you can use to help in sprayer calibration, nozzle selection, tank mixing, and product selection.