Integrated Pest Management (IPM) Scouting for Vegetables
Funded by USDA Specialty Crop Block Grant Project ME#44166076 – “Sustainable Production and Pest Management Innovations for Next Generation Young and Hispanic/Latino Specialty Crop Growers”
The cornerstone of a good integrated pest management program is thorough and frequent scouting.
Scouting is going to allow you to find out if you have a problem before it gets out of control, And with scouting you're also going to know if you're at the point where it is an economic problem And avoid unnecessary sprays That's good for the environment, and good for your pocketbook So, I know you guys are busy, but scouting from the truck doesn't work too well That's a little closer. Now you can see a few things, but in order to scout you really want to get down into the canopy so that you can see an accurate idea of what's happening.
You're going to want to walk your fields looking at representative plants throughout the field and especially in areas where problems are likely to start, so like wet areas or along field edges.
It is best to scout once a week starting when the pest or disease is likely to be in the area. There are good tools such as pest watch and NEWA: Network for Environment and Weather Applications which can give you alerts that conditions are ripe or that there are pests or diseases in your area.
Different crops, pests and diseases require different scouting methods.
Many problems you are going to be able to detect with visual observation.
For some it will be helpful to use a hand lens, a sweep net, or a trap. In other cases you might need to dig up those plants and look at the roots.
Visual observation works well to monitor exposed feeding insects such as Colorado potato beetles, aphids, leaf miners, cucumber beetles, fleabeetles and plant diseases that affect the leaves and fruit.
Randomly select plants throughout the crop. Often walking a W pattern will help you see different parts of the field. Examine the upper and lower leaves, the growing point, where the stem enters the ground and any fruit that might be present. A 10X hand lens will help distinguish identifying characteristics.
Scouting for tomato diseases is an example of visual scouting. Early blight, septoria, bacterial diseases and late blight can all cause serious problems in tomato plantings.
Make sure to scout for tomato diseases once a week throughout July and August. It is really helpful to pay attention to TomCast which will help you predict when conditions are right for diseases like early blight and Septoria or BLITECAST for late blight, and this well also help you decide when you want to be scouting On each date randomly select 10 plants evenly distributed in the field. Keep in mind trouble spots, like wet areas or field edges but don’t focus entirely in those areas.
Examine the upper and lower leaves in each of ten areas.
Note which diseases are present and which percent of the plant leaf is affected. It is important to scout each cultivar separately or note which ones are affected.
Onion thrips can cause up to 60% losses. To scout for onion thrips look in the cracks and the crevices of the onion. Make sure to check up the leaves as well to count all the thrips on the leaves. When scouting for onion thrips count thrips on five plants at ten different locations scattered throughout the field.
When you are done counting add up the number of thrips and divide by fifty and then calculate the number of thrips per plant.
Then divide by the average number of leaves per plant.
When using insecticides the threshold for treatment is 1 thrip per leaf except for radiant where the threshold is 3 thrips per leaf.
Small insects you might miss otherwise are more easily monitored with a sweep net. They work well on low growing crops that can stand some battering.
Potato leaf hoppers, flea beetles and tarnished plant bugs are easier found with a sweep.
Sweep the net in an 180 degree arc from right to left and back.
Make sure to go from the top to near the bottom of the plant with some vigour without hitting the ground.
Generally you take ten sweeps each time in 5-10 areas of the field.
Average the number of insects you find across the 10 areas and check it against your threshold.
Blacklight, pheromone, and sticky traps can help in monitoring.
Pheromone traps are pest specific. A lure inside the trap emits a sex pheromone specific to the insect you want to monitor.
Corn borer and earworm use hartsack pheromone traps.
Spotted wing drosophila and others can use a bucket trap.
Sticky traps should be placed at the level of the crop canopy.
Sometimes you don't need to see the insect to know you have a problem Learn to recognize different types of damage.
I like to have a kit ready when I go out to scout.
Make sure you have a knife, pruning shears, a hand lens, a notebook, and all the other tools you'll need.
Frequently Asked Questions