Food Gardening in Massachusetts 2020 Vol. 1:13

Pest management is an important topic in the production of vegetables and herbs. Commercial farms need to be economically viable in order to be successful and managing pests so that they do not cause reductions in yields and thus profit, is an important component of their overall economic sustainability. Normally, there is not the same economic imperative for home gardeners; however, there are practices gardeners can follow to address pest issues, both preventatively and after pests appear, to increase production and quality of their vegetables and herbs. 

We’ll begin by briefly discussing Integrated Pest Management (IPM), a holistic approach for managing agricultural pests that was developed for use by commercial farmers. The concept of IPM was first developed in the early 1970s and is constantly being updated and improved through research undertaken at land grant universities, including the University of Massachusetts, in collaboration with other institutions around the world. 

Many of the concepts used in the implementation of IPM, although developed for commercial farmers, are also relevant for managing garden pests. We recommend you read  “Overview: Integrated Pest Management” found in the New England Vegetable Management Guide (NEVMG). As described in this article, a critical component of IPM is the accurate identification of the target pest, be it an insect or disease. It’s helpful to know the scientific name as well as the common name of the pest, because some common names are used for multiple diseases or insects. (For reasons described below, it is not as important to know the names of weeds you have in a garden in order to manage them.)

Most commercial farmers use pesticides on their farms, whether they are organic or conventional. The Environmental Protection Agency (EPA) regulates the use of all pesticides in the United States, including all pesticides for commercial growers, home gardeners, lawn care, ornamentals…the list goes on. Here is their definition of what constitutes a pesticide: What is a Pesticide?  

• Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.
• Any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant.
• Any nitrogen stabilizer.

From our work with people growing food in urban gardens, we know that there is a lot of interest in growing food using organic practices. Here’s a little history and background of organic agriculture in the United States:

Before 1990, the term “organic”, as it relates to agriculture, meant different things in different states—produce that could be called “organic” in one state wouldn’t necessarily meet the standards of another state. In 1990, legislation was passed by Congress to streamline the definition of “organic.” In 2002, the National Organic Standards that resulted from this legislation established practices that must be followed for agricultural products to be labeled “certified organic”, including allowable pesticides and fertilizers. Pesticides and fertilizers are approved for use on organic produce by the Organic Materials Review Institute (OMRI) and are therefore called “OMRI-approved” materials. The process for establishing what was, and what was not, a certified organic pesticide was intense, to say the least, and was a fascinating process to follow! The SARE program has a brief summary of the process – History of Organic Farming in the United States.

Farmers interested in growing and selling certified organic products have to contract with entities authorized by USDA the USDA Agricultural Marketing Service to become certified organic. In MA, Baystate Organic Certifiers is currently the only organization that can provide this certification; other certifiers operate in other states. The process to become certified organic is extensive, comprehensive, and costly. Some growers follow the requirements for organic certification but choose not to get certified, as getting and maintaining organic certification is time-consuming and expensive; these farmers cannot market their produce as “certified organic” unless they sell less than $5,000 per year of agricultural products. What farms and businesses are exempt from organic certification? According to this rule, I could sell the vegetables and herbs we grow in our home garden as “organic”.

The term “conventional” is used for agricultural products that are not certified organic. This could include produce grown on farms that use synthetic pesticides and fertilizers, farms that use no pesticides or chemical inputs, or use only OMRI-approved materials but choose to not become certified organic. Integrated Pest Management can be implemented by any farm, conventional or certified organic.

I have had a vegetable garden for over 25 years, where I rarely use pesticides, be they certified organic or conventional. This is a personal preference, and it is not to suggest applying appropriate pesticides in appropriate situations in your garden is not warranted. So far this season, I have not applied any pesticides on any vegetables or herbs in my garden, even though I have had issues with insects, diseases, and weeds. I will share information below on specific pest issues I have had so far in my garden and how I have managed them, or not, and the reasons for both decisions. 

A key component of pest management is following practices that promote healthy plants, because heathy plants are better able to defend themselves from pest damage. Conversely, a stressed plant is much more susceptible to damage from pests: Plant Defenses, Management Practices, and Pests.

Here are some general guidelines to follow to foster optimum plant health to minimize plant stress and pest damage.  

1. Maintain an appropriate amount of water in the soil for your vegetables and herbs. Too much water can cause diseases and insufficient water can lead to plant stress followed by pest colonization. This topic is covered in the column Water Management for Vegetables and Herbs in Your Garden, published in this series on June 8th. 
2. Don’t plant or seed vegetables and herbs too close together. This is tempting to do, thinking the closer together you plant/seed your plants, the more you’ll harvest; however, doing this will cause the opposite effect. Tight plant spacing reduces air movement between plants, leading to longer leaf wetness periods and potentially more disease. Tight plant spacing can also increase competition for water and nutrients among plants, leading to lower crop quality and yields. Follow the recommendations for plant spacing on the seed package or on the tag that comes with a transplant you buy. You can also check out the spacing for vegetables and herbs listed in the New England Vegetable Management Guide. For example, the recommendation in the NEVMG for pepper transplants is to space 12"-18" apart in the row and 3' - 3.5' between rows. (Note: the reason for the 3’ to 3.5’ between rows is because most commercial farmers, the main audience for the NEVMG, need space for their tractors to straddle the rows, which is why many put double rows on one bed (Figure 1).  
3. Make sure you have the appropriate soil nutrient levels for your crops. Crops will provide optimum yields and be better capable to resist pests when they have the recommended amount of plant nutrients in the soil. Too much fertility can be just as detrimental as not enough, causing delayed maturity and decreased resistance to pests. As detailed in the first column in this series Welcome, Soil, Soil Testing and Peas and click on “The Importance of Soil and Soil Testing for Growing Edible Crops