Integrated Weed Management: Weed Scouting for Vegetable Production
Integrated Weed Management in vegetable production starts with scouting and identifying weeds. This video describes resources for identifying weeds, and methods for scouting and recording weed populations in different types of vegetable production systems.
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”
- [Instructor] Weed scouting in vegetables.
Scouting for weeds is an important management practice that can have a significant impact on your farm's bottom line.
In this video we'll give you the information you need to effectively scout your vegetable crops as part of your weed management program.
So why are weeds a problem in vegetable crops?
Weeds are a major concern in any agricultural production system.
They compete with our crop for important resources like light, nutrients, and water.
Weeds can also be a haven for pests, things like diseases, insects, and rodents.
Weeds also create difficult working conditions and can greatly slow down crop harvest.
To best manage weeds in any planting it's important that we first know which weeds are present in our fields, at what density they are present, and at which growth stage they are.
We do that by scouting.
Scouting should be performed early and often in the season.
That's because weed seedlings are much easier to control with an Integrated Weed Management Program when they are still very small.
We're going to talk about how to scout for weeds in vegetable crops, and how to use the information that scouting provides.
Identifying the weeds that you find through scouting is very important.
You can't manage weeds without knowing what they are.
There are many weed guides available to help you determine which species are prevalent in your field.
Weeds of the Northeast is a very thorough guide with excellent descriptions.
Stubborn Weeds of Pennsylvania contains pictures of most of the problematic weeds commonly found in Pennsylvania fields, and this is available in both English and Spanish.
This guide has many color images and describes key traits of each weed, for proper identification.
You can also learn about these weeds on the Penn State Extension Website.
In addition to a weed guide, some additional items will help you make your weed scouting as effective as possible.
Bring along a notebook to record notes on the field.
A hand lens will allow you to look at difficult to see features, things like hairs on the surfaces of the leaves.
A field map will let you record the location of weed patches so that you can easily find them again later.
If you don't recognize a weed, it's often useful to bring it with you to identify later.
Bring plastic bags and markers to collect weeds for this later identification.
A quadrat can be useful when counting plants to assess weed density.
You can make one yourself using PVC pipe, or you can also use a folding ruler.
A two by two foot square will do just fine.
When scouting vegetables, or any crop, good note taking is critical.
When you see weeds in your crop record the species and it's growth habit.
Because weeds get more difficult to control as they mature, record the growth stage and size of the weeds you find.
Be sure to record the location of the weeds, whether in your notebook or on a field map.
Make notes of which crop you found them in and how dense they are.
Now let's review scouting protocols for two distinct vegetable production methods commonly used in Pennsylvania.
Growing crops on flat ground and growing crops on raised beds with plastic mulch.
Crops that are direct-seeded onto flat ground, like sweet corn, may have increased early competition from early annual weed emergence.
Many vegetable crops are grown on raised beds with plastic mulch and drip irrigation.
A big concern here is controlling annual and perennial weeds growing in the paths between the mulch beds.
Let's take a closer look at scouting sweet corn and other vegetables produced on fields without beds.
For timing, you'll want to begin scouting prior to planting the field.
Use your scouting notes from previous years to check areas of the field where you know you have problem weeds.
Take notes so you can best plan your pre-plant weed management program.
Once the crop is seeded or transplanted, you'll want to scout at regular, frequent intervals because weeds are most competitive when vegetable crops are young.
During this crucial stage, plan to scout at least weekly.
In sweet corn you'll want to scout well before the corn is six inches tall to evaluate your Spring weed control program, and to control any new weeds that may be coming up.
Remember, you don't need to wait for a weed scouting trip to be on the lookout.
Keep a notebook with you when performing other work in the field.
If you see a weed problem, take notes, so you can respond quickly.
In your smaller fields scout your entire field to be thorough.
In larger fields use a zig-zag, X, or W pattern to scout representative areas of your field.
Stop and make close observations at a minimum of 10 locations.
Be sure to look closely for small emerging weed seedlings.
Many vegetable crops are grown on raised beds with plastic mulches.
These mulched beds can help reduce weeds, but they must be scouted to catch potential problems early.
After beds have been shaped, a pre-emergent herbicide can be applied to the beds and then the plastic can be laid down.
Make sure to follow all herbicide labeled directions when making applications under plastic mulch.
From here, weed scouting will primarily focus on preventing annual and perennial weeds from establishing within the field, primarily between mulched beds, but also growing out of the transplant holes.
For raised bed systems, scout the field prior to laying the raised beds, then weekly following planting.
On small fields walk the entire site, but on larger sites you can walk the planting in a zig-zag, X or W pattern.
Be sure to pay close attention to where the crop is coming through the plastic in addition to the row middles.
Some crops, like onions, are particularly poor competitors with weeds growing through the plastic, and the weeds will grow rapidly if they're not controlled early.
Take detailed notes, as previously described, and mark the location of each weedy area on your field map.
Here's an example of a pattern to walk for scouting your vegetable fields.
Remember to take notes at least at 10 locations as you walk, and make other notes about weeds as you see them.
Also check areas of your fields that you know have a history of having problematic weeds.
We've talked about using notebooks and field maps to collect detailed scouting information through the season.
Weed maps can be a useful tool for summarizing the most important scouting finds and recording that for reference from year to year.
Weed maps can take many forms.
They can be hand drawn maps on paper, digitized maps, or even part of mobile apps.
The important thing is to use weed maps as a central place to compile and record the most important information on weeds in each field.
Refer to these maps when planning crop rotations, tillage operations, and herbicide application, timing, and materials.
The information that you gather scouting weeds will help you make better decisions when it comes to weed control and crop rotation.
Scouting helps you to identify and control weeds early, when they are in their most vulnerable stages.
Problem weeds can be found early and spot-treated to minimize their spread.
Scouting throughout the season let's you evaluate how well your weed management program is working.
For more information on weed management and other topics related to vegetable production you can contact your local Penn State Extension Educator, attend a vegetable production event or course in your region, and find out more online at extension.psu.edu.
The Mid-Atlantic Commercial Vegetable Production Guide is another source of detailed information on Integrated Weed Management.
Frequently Asked Questions