Integrated Weed Management: Weed Scouting for Fruit Production
Integrated Weed Management in fruit production starts with scouting and identifying weeds. This video describes resources for identifying weeds, and methods for systematically scouting and recording weed populations in orchards.
This video is also available in Spanish.
- [Narrator] Weed scouting and tree fruit.
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 tree fruit as part of your weed management program.
Why are weeds a problem in tree fruit?
Weeds compete with fruit trees for light, water, and nutrients.
They harbor insects and diseases and serve as reservoirs for viruses.
Weeds also provide cover for voles and other rodents.
All of these can reduce fruit yield and quality.
In addition, weeds can impede pesticide coverage.
It can cause undesirable conditions for workers.
Weed problems in orchards can be assessed by surveying or scouting the orchard floor periodically during the growing season.
The objectives of weed scouting in orchards are to determine weed abundance, to identify prevalent weeds that should be controlled with a base herbicide program, and to identify problem weeds that may require spot treatments.
All of these objectives require correct identification of the weeds.
There are many 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 many weeds commonly found in Pennsylvania and is available in English or Spanish.
The publication has many color images of the weeds and describes key traits for proper identification.
You can also learn about weed identification 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 take notes on what you see.
A hand lens will allow you to look at difficult to see features, like the ligules of different grasses.
A field map will let you record the location of weed patches so that you can easily find them later.
If you don't recognize a weed, it's often useful to bring it back with you to identify later.
Bring plastic bags and markers to collect weeds for later identification.
Bring a quadrat to record weed density.
You can make one yourself using PVC pipe or you can also use a folding ruler.
You can use nearly anything so long as you can make a square for sampling.
There are two methods for surveying orchard weeds, orchard scanning and plot sampling.
Both methods yield reliable information, but a drawback of orchard scanning is the time required to obtain an adequate number of samples.
So instead we describe the plot sampling technique.
In this method, sampling is conducted at 10 randomly selected trees within the orchard block.
This method saves time and can also be combined with routine insect and disease monitoring.
Weed scouting should be performed at least three times during the growing season.
In early April, in mid June, around June drop, and at the end of August.
Scouting at these three times will help you manage weeds that emerge at different times throughout the growing season and will help prevent perennial weeds from establishing.
When scouting for weeds in your orchard, you should walk through each block in a zig-zag, X, or W pattern so that you can assess weeds throughout each block.
To scout select 10 trees at random that are approximately evenly spaced throughout your block.
Use your quadrat or a folding ruler to form a two by two foot frame.
Place the quadrat in the tree row at the base of the tree or between two trees.
Position the frame so that the weed population inside the quadrat is representative of the ground cover under each tree.
Count only the weeds that emerge from the soil within the quadrat.
In your notebook, record the total percentage of ground within the quadrat that contains weeds.
Then estimate what percentage of the total weeds are grasses and what percentage are broadleaf weeds.
This will help you develop the best management strategy.
Finally, take a few moments to estimate the percentage cover for major weed species that are present.
Once you have collected your information at all 10 trees, calculate the 10 tree average for percentage of weeds, percentage of broadleaf weeds and grasses, and percentage of specific weed species.
Penn State has an apple scouting spreadsheet that can automatically calculate your averages for you.
This tool is also available as part of a smartphone app for tree fruit scouting.
As you walk between the trees you will collect quadrat data from, look around and take notes for any troublesome perennials you might find that require immediate attention, like Poison Ivy, Canada Thistle, and Yellow Nutsedge.
Also note any broadleaf weeds in the row middles that can serve as reservoirs for viruses.
Some of which include Broadleaf or Curly Dock, Broadleaf or Buckhorn Plantain, or Dandelions.
For these problematic weeds, write down as much detailed information as you can.
Record the species and its growth habit.
Because weeds become increasingly 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 on their coverage and how dense they are.
If you see a weed you don't recognize, bring a sample back in a plastic bag to identify later.
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 block.
With this scouting information, you can fine tune your annual orchard herbicide program to best manage weeds in the spring and make any spot treatments to problematic weeds throughout the orchard as they appear.
Your late season scouting will help you keep your orchard clean through harvest and help you evaluate your yearly weed control methods.
For more information on scouting for weeds in the orchard, speak with your local Penn State Extension educator or attend a commercial fruit grower meeting in your region.
You can also visit the Penn State Tree Fruit site for fact sheets and bulletins and to download the apple tree scouting spreadsheet or smartphone app.
For even more tree fruit information consider purchasing the Penn State True Fruit Production Guide.