Whether you are producing tomatoes commercially or have a few pots in your backyard, your plants can and will fall victim to pests. Why? Because you are creating a perfect environment and food source for many invertebrates such as insects. The following information pertains to general pest management practices and prevention. At the bottom of the article, there is a list of good resources for Integrated pest management (IPM) practices and if you are in the United States, how to find your local extension office.
In order to control any pest, you must know your enemy! Or, if it your newfound friend is actually your enemy versus a beneficial insect or neutral organism. If you aren’t sure what your pal is, you can always contact your local cooperative extension office or send us a request. Once you have identified your buggy friend (or foe), determine what methods you can use to control their populations if necessary.
Before treating any plant, it is important to determine and adhere to thresholds. For example, one spider mite is not really an issue. One acre of spider mite-infested tomato plants is! In commercial uses, this threshold is usually set by the economic value of the crop versus treatment. Each individual crop has different thresholds. With tomatoes, it depends on the location, variety, size of crop, and time of year. Younger plants have lower thresholds than older plants since the older plants are generally stronger.
You need to study and evaluate your plants. If you have had issues with specific pests in the past, keep an eye out for them. Depending on the pest, you can use sticky traps, pheromone traps, or even take scheduled soil samples to check pest levels. In order for this to be effective over time, you should have consistent parameters set such as how far apart your traps are and how often they are checked or changed. Recording this data while observing your plants’ health can determine how many pests are too many.
Integrated pest management (IPM) uses several control methods in order to reduce pest populations, especially within crops where thresholds have been met. The best results are seen when you combine multiple methods from the following categories.
Prevention is key! The cheapest and easiest way to rid your plants of pests is to keep them from ever building populations. Removing additional sources of food, shelter, or water can deter pests (*see note in biological controls). Blocking access to plants by using various barriers or making sure your greenhouses are well protected is another good place to start.
Cultural controls are practices that also discourage pest invasions. Make sure to remove debris and any infested/diseased/dead plant material from the area. Your plant health is also extremely important! Small infestations will only have large impacts on plants that are not watered or fertilized properly. Adjusting planting times can also be helpful. If a known pest is most active during a particular time of year, try planting a variety that does well earlier in the year. By the time your pest populations increase, your plants will be stronger and healthier to combat any damage. The goal of cultural controls is to disrupt the habitat for the pests. Breaking up your crops by adding other plants (known as polyculture farming) can mimic natural ecosystems. When you think of a wild field or forest, are all the plants the same as with crops? Of course not. Most crops are grown as monocultures (one type of plant) which creates the perfect habitat for a small few species of insects while depleting resources for natural predators. Adding “trap crops” can also be added to this category. Some tomato pests actually prefer other plants. Adding small crops of their preferred host plants will attract them away from your tomatoes. Make sure when you are choosing tomato varieties you are looking at what does best in your area. As we said earlier, healthy plants are less susceptible to severe injury from pest damage and disease. There are also pest-resistant varieties available, so do your research!
Mechanical controls are a minor part of most IPM programs. A good example is knocking pests off plants by spraying water or even picking them off by hand. Traps can also be used not only for monitoring thresholds but also for decreasing pest populations.
This control uses natural enemies (beneficial organisms such as insects or bacteria) to help manage pest populations. There are many species of beneficial insects available commercially for purchase. While many of these can be effective, please remember that in most outdoor situations they often disappear. They are most effective in greenhouses, hoop houses, or if your plants are netted. Before purchasing any beneficial insects, make sure to do your research. Often times climates or incorrect or even worse, the “beneficial” you ordered may become invasive, destroying local ecosystems.
You can encourage natural (and local) enemies by planting nectar-producing plants and not using broad-spectrum pesticides. In the prevention category, we mentioned removing shelter, water, and food availability. Please do this at your discretion if introducing beneficial insects or trying to attract them. These items may attract pests, but they can attract beneficial insects too.
Pesticides can be effective, but should only be used after non-chemical methods have been exhausted. Try to find pest-specific chemicals or the least toxic materials available that are still effective. Instructions should be followed carefully, including the reduction of human and pet exposure while also trying to protect the environment. Pesticide treatments are most effective when used with the other methods mentioned above. Once your pests are controlled, revert to using preventative and non-chemical methods to keep them from resurfacing. Once pests are controlled, use preventive non-chemical methods to keep them from coming back.
Lauren Davidson
World Tomato Society Entomology Expert
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