Integrated Weed Management for Fruit and Vegetable Production
Two associated videos, Weed Scouting for Vegetable Production and Weed Scouting for Fruit Production, provide more details on weed identification and field scouting procedures.
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”
- [Lee] Integrated Weed Management for Fruit and Vegetable Crops.
Managing weeds is one of the most challenging aspects of growing horticultural crops like tree fruit, berries, grapes, and vegetable crops.
Weeds are a problem in these production systems for a variety of reasons.
They compete with the main crop for nutrients, light, and water, they harbor pests and diseases, and weeds make field work and harvest difficult.
Successfully managing weeds can have a significant impact on your farm's bottom line.
In this video we'll give you the information you need on strategies to use to control weeds through an integrated weed management approach.
The very first steps in integrated weed management are monitoring or scouting and identifying weeds.
You cannot manage weeds without knowing what they are and where they are in your fields.
It's very important to know whether you're dealing with grasses, sedges, or broadleaf weeds and whether they're annuals or perennials.
In fact, these steps are so important that they're covered in two separate Penn State Extension videos: Weed Scouting in Vegetables and Weed Scouting in Tree Fruit.
These two videos discuss resources for identifying weeds, like the Penn State publication Stubborn Weeds of Pennsylvania and procedures for systematically scouting and recording weed populations in your fields and orchards.
Weed scouting and weed identification provide the baseline information you need for making weed management decisions.
Let's look into our integrated pest management, or IPM toolbox for appropriate tools that we can use in our integrated weed management approach.
We can successfully manage weeds in fruit and vegetable crops using a combination of IPM tactics, including prevention and avoidance, suppression, mechanical control, and chemical control.
Unfortunately, we don't currently have very effective biological control agents for weed control in these crops, but we have a lot of options with the other four tools.
But no matter what control measure you're going to use, remember that timing is critical.
Weeds are much easier to kill when they're small.
They say that an ounce of prevention is worth a pound of cure, and nowhere is that more true than in managing weeds in fruit and vegetable crops.
Preventing weeds from becoming established and avoiding the spread of weeds should be an underlying crop management goal throughout the growing season.
A single weed has the ability to produce hundreds to thousands of seeds, so it makes sense to prevent weeds from going to seed and building up the weed seed bank.
Avoid spreading weeds through equipment, mulch, or soil amendments like manure or compost.
Perennial weeds can be particularly difficult to manage.
Use crop rotations to help contain those tough weeds.
Weeds need light and space to germinate and to grow.
There are a number of ways to suppress weed growth, including the use of mulches and cover crops.
Setup crop row spacings that allow the crop to close up the canopy so that weeds are shaded out.
Mechanical weed controls include tillage, cultivation, hand weeding, and flame weeding.
Tillage tools like moldboard plows can bury weed seeds, roots, and rhizomes deep below the surface where they cannot grow.
Surface tillage tools like discs and harrows chop up and kill weeds.
But surface tillage tools can also make a perennial weed problem worse by spreading many pieces of roots or rhizomes that sprout into new weeds.
Cultivation tools disturb just the very surface of the soil primarily to kill weeds.
Cultivation tools include tractor-drawn implements, self-propelled units, and hand tools.
Hand weeding is a less pleasant but sometimes necessary form of mechanical weed control.
And some growers use flame weeders of various designs to control weeds.
A wide variety of specialized cultivation tools are manufactured for fruit and vegetable growers, particularly for organic growers.
Some of these include tine weeders, belly mounted sweeps, grape hoes, and an assortment of efficient hand tools that are especially useful in small plantings and high tunnels.
And finally, we have chemical controls or the use of herbicides.
It's important to understand several key concepts about how different types of herbicides work.
Herbicides labeled for weed control may be pre-emergence or post-emergence herbicides, selective or non-selective herbicides, and contact or translocated.
Pre-emergence herbicides are applied to the soil or growing media prior to the germination of annual weeds.
They need moisture for activation.
There are pre-emergence herbicides that are effective on grasses and on broadleaf annual weeds, but pre-emergence herbicides have little to no effect on perennial weeds.
In contrast, post-emergence herbicides are applied after weeds have emerged and have little to no soil activity.
There are post-emergence herbicides that are effective on grasses and broadleafs, both annuals and perennials.
Post-emergence herbicides may be applied after crop planting, over the top of the crop, or directed away from the crop.
Post-emergence herbicides can be selective or non-selective in killing weeds.
Selective herbicides kills some types of plants, but do little or no damage to others.
For example, there are a number of post-emergence herbicides that will kill grasses but not broadleaf weeds.
Non-selective herbicides kill or injure almost all plants they contact.
Roundup, or glyphosate, is an example of a non-selective herbicide.
Post-emergence herbicides can be contact or translocated.
Contact herbicides kill or injure the contacted part of the plant.
Translocated herbicides move within the plant and are often used to control tough perennial weeds.
Herbicide use in fruit and vegetable crops is a complicated subject.
Penn State Extension's production guides for tree fruit, berries, grapes, and vegetables provide a great deal of detailed information on the safe, legal, and effective use of herbicides in these crops.
In all cases, follow herbicide label instructions and take steps to protect yourself from pesticide exposure.
We've talked about all of the different tools and strategies we can use to manage weeds.
None of these used alone will result in good weed control.
Rather, we want to use them in a suite in creating an integrated weed management approach.
This involves using the information you gain through scouting and weed identification and using multiple control measures for best results.
Once again, when it comes to weed control timing is critical.
Get them when they're small.
Let's look at a couple of examples of how an integrated weed management approach is used in a crop production system.
In Pennsylvania many vegetables are grown on raised beds covered in plastic mulch.
In this system crop rotation aids in prevention and avoidance of weeds.
Tillage and hand weeding provide mechanical control, plastic mulches provide suppression, and herbicides are used between mulched beds.
Another example is in establishing a new vineyard.
Site preparation for a new vineyard is usually performed over a period of one to two years.
During this time weeds are controlled through a combination of tillage and herbicides and suppressed through cover crops.
When the vines are planted, herbicides and cultivation are used to keep rows weed-free while the young vines become established.
A final example is annual strawberry production, which is a system that's gaining popularity in Pennsylvania compared to the more traditional matted row system of growing strawberries.
In annual strawberries, weeds are prevented through crop rotation and cover crops, suppressed by plastic and organic mulches, mechanically controlled by tillage and cultivation, and chemically controlled by herbicides.
For more information on integrated weed management and other topics related to fruit and vegetable production, you can contact your local Penn State Extension educator, attend a fruit or vegetable production event or course in your region, and find out more online at extension.psu.edu.
Penn State Extension's vegetable, tree fruit, berry, and grape production guides are another source of detailed information on integrated weed management.
Frequently Asked Questions