Treatment Options

Cultural Control

Cultural control options include tilling debris, rotating crops, using cover crops, applying proper irrigation and nutrition, improving soil health, using resistant varieties, and other similar methods.  Often, practicing proper cultural controls throughout the year is enough to keep most pests in check.

Trap Cropping

Trap cropping involves growing plants alongside a target crop that are more appealing to certain pests, thereby protecting the crop. It is an important cultural control method within IPM that is not widely used in Utah. But when successfully implemented, trap cropping provides a sustainable, long-term management option.

There are several types of trap cropping, characterized by plant type, where the plants are grown within the farm, and when they are planted.

  • Conventional Trap Cropping – A traditional and proven-effective plant is planted around or within the cash crop that is more attractive to a target pest as either a food source or for reproduction.
  • Dead-End Trap Cropping – using plants that are attractive to a target pest but on which offspring will not survive. Dead-end trap crops serve as a “sink” and prevent movement of the target pest to a cash crop later in the season. Dead-end trap crops are planted in field borders or edges where they intercept insect pests.
  • Genetically-Engineered Trap Cropping –  plants may be genetically engineered to act as a trap crop. Preventing insect-vectored diseases is one example, where the trap crop is capable of harboring a certain virus but its insect vector cannot acquire it from that plant. In this example, the trap crop helps reduce the insect-vectored pathogen as opposed to the insect itself.
  • Perimeter Trap Cropping – planting trap crops around the border of the main crop.
  • Sequential Trap Cropping – traps crops that are planted either later or earlier than the main crop to increase the attractiveness to insect pests during certain times of the season.
  • Multiple Trap Cropping – planting several trap crop species to manage several pests or controlling a target pest by combining plants whose growth stages enhance attractiveness season-long.
  • Push-Pull Trap Cropping – a combination system where a trap crop is planted around the perimeter of a crop to attract the target insect pest (pull) and a different plant is inter-cropped to repel (push) the insect away from the cash crop.
  • Biological Control-Assisted Trap Cropping –  trap crops that are planted within and around the crop that enhance populations of natural enemies that then help suppress multiple pests.
  • Semiochemical-Assisted Trap Cropping – using either manually hanging insect semiochemicals (such as pheromone lures) on a perimeter planting, or using genetically modified plants that emit semiochemical lures to attract the target pest. pest.

Examples of Trap Cropping Options in Utah Vegetable Production

Cash Crop Insect Pest
 Trap Crop
Broccoli Potato Leafhopper Various Mustardss
Cabbage Cutworms Chinese Cabbage, RadishC,S
Cabbage Diamondback Moth Various Mustardss
Cauliflower Colorado Potato Beetle Chinese Cabbage, Marigolds, SunflowersM
Cruciferous crops Flea Beetles Various Mustardss
Cruciferous crops Cabbage Maggot Chinese Cabbage, TurnipsC
Cucurbit crops Cucumber Beetles Specific Varieties of Cucurbit CropsC,S
Sweet Potato Wireworms Corn,WheatC,S,SA
Curubit crops Squash Bugs Hubbard SquashesM,S
Lettuce Aster Leafhopper LettuceS
Lettuce Thrips Various WildflowersC,P
Sweet Corn Stink Bugs Various MustardsC,P
Tomato Colorado Potato Beetle PotatoS
Tomato Whiteflies SquashC
  • C=Conventional
  • P=Perimeter
  • SA=Semiochemical Assisted
  • M=Multiple
  • S=Sequential.Early,and/or Late Planting

Mechanical Control

Options usually involve methods to exclude pests such as applying row covers, disking weeds, and good sanitation practices (keeping tools clean, promptly removing unhealthy plants, etc.). 

Row Covers

Various cover options are available. Lightweight materials (approximately 0.5 ounces per square yard) are effective as an insect barrier starting in late spring. The material may be non-woven, spun-bond fabric with 90%-95% light transmittance. Heavier fabrics (1.5 ounces to 2 ounces per square yard) are used to extend the growing season by protecting the crop from early or late frosts. These thicker materials allow for 50%-70% light transmittance. A few common brands of the spun bond fabrics include Agribon and Reemay. Ventilated plastic covers are also available for heat retention. Woven materials include thicker fabric or plastic mesh. For example, the Proteknet brand of mesh is available in six grades ranging in sizes from 0.85 mm2 to 0.85 mm x 1.4 mm (Table 3.2). Ensure the pest being controlled will not be able to pass through the selected mesh grade. Row covers can be purchased online through garden supply and seed companies or may be available at some select garden centers.

When selecting the support structure for row covers, consider whether it will be used for a single season or multiple uses. Options include 3/4-inch PVC that can be bent, metal hoops, or small wire hoops. When constructing your row covers, first decide which crops to cover. Then, identify the purpose of the cover. For example, if the purpose is insect exclusion, be aware that timing is important. Understand when the pests can be most destructive to the crops and plan to leave the covers up for that duration of time. Also consider timing and crop size for row cover height.. The structure can be built over existing beds and rows with plastic mulch and drip line. First, install the PVC, metal, or wire hoops, then lay the cover over the frame and secure with binder clips. A tight seal to the ground is important, but avoid using stakes or anything that could tear the material. 

Insects Excluded from Various Netting Mesh Opening Sizes

Species
 0.0138"2
 0.0335"2 0.05" x 0.7" 0.19" x 0.12"
Aphids X      
Flea Beetles X      
Lacewings X X X  
Ladybugs X X X  
Leafhopper X X    
Lygus Bug X X X  
Moths X X X X
Root Maggot Flies X X X  
Stink Bugs X X X X
Spider Mites X      
Squash Bugs X X X X
Thrips X      
Whitefly X      

More Information

Biological Control

For greenhouse or high tunnel crops, biological control by releasing organisms works very well for controlling many insects and diseases.  Because some insects used for biocontrol tend to disperse after release, they are not suitable for use on crops grown in the field.  A better alternative is to enact measures that conserve and promote naturally occurring beneficial organisms through border or edge habitat plantings, applying compost to soil, and reducing pesticide use.

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Chemical Control

If you determine that a pesticide is needed for treatment, be aware that for insects (and many diseases), treatments should be applied only during the time period when the most susceptible life stage is active.  For example, leafhopper on potato is most easily treated before the young (nymphs) develop wings.  Once they can fly, they can avoid the insecticide application, and they are already producing new offspring to infest the crop.  In addition, you find feeding symptoms but identify no causal insect, a chemical spray is not recommended.  

Pesticides are grouped by mode of action (how they kill the target organism), which is usually designated by a group number.  Pesticides with similar active ingredients will have the same number.  Rotating among pesticides in different group numbers will reduce the likelihood of pest resistance.  

For each pest group (insects, diseases, weeds), there are many pesticide options.  Products that are “broad-spectrum” kill a range of organisms, including beneficial ones, whereas other options target certain species and are less toxic.  The EPA’s Conventional Reduced Risk Pesticide Program registers certain pesticides as “reduced risk.”  These are pesticides that pose less risk to human health and the environment than existing conventional alternatives.  (Biological and antimicrobial pesticides are all reduced risk but are handled through separate registration processes.) 

Products given the Reduced Risk designation have:

  • Low impact on human health.
  • Low toxicity to non-target organisms (birds, fish, plants).
  • Low potential for groundwater contamination.
  • Low use rates.
  • Low pest resistance potential.
  • High compatibility with Integrated Pest Management (IPM) practices.     

How to Make Row Covers

Trap Crops