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Weed Management in StrawberriesMatthew Cutulle
Overview of Weed Management
“If you know the enemy and know yourself, you need not fear the
result of a hundred battles. If you know yourself but not the
enemy, for every victory gained you will also suffer a defeat. If you
know neither the enemy nor yourself, you will succumb in every
battle” –Sun Tzu (Art of War)
https://www.clemson.edu/cafls/research/weeds/index.html
Understanding Critical Weed Free Period
Weed and crops are not competing
Weed interference will not Impact crop yield
When Weeds Become a Problem?
Weeds as Indicators of Poor Growing Conditions
Condition Indicator Weed(s)
Low Soil pH Red Sorrel
High Soil pH Plantains
Droughty Soils Prostrate Spurge, Black Medic, Knotweed, Woodsorrel,
Lespedeza, Bracted Plantain
Wet Soils Sedges, Poa annua, Alligatorweed, Moss, Algae, Goosegrass
Poor (Sandy) Soil Quackgrass, Poorjoe, Sandspur
High Nematodes Spurges, Pusley, Knotweed
Compacted Soil Goosegrass, Poa annua, Knotweed
Low Soil N Legumes (Clover, Chickweed, Black Medic, Chicory,
Speedwell), Broomsedge, Yellow Sneezeweed
High Soil N Poa annua, Chickweed, Moss, Ryegrass
Weeds as Indicators of Poor Growing Conditions
Stale Seed Bed Technique
• A stale seedbed is a seedbed where the non-dormant weeds in the germination zone (shallow soil layers from which weeds can emerge) are killed before crop planting. Weed emergence from the germination zone depends on weed species, soil type, tillage, and soil physical characteristics.
Prevent Seed Rain
Plasticulture
Impact of mulch color on yield
0.00
50.00
100.00
150.00
200.00
250.00
3 4 7 11
Wei
ght
(ou
nce
s)
Rep
Cama Rosa
Yellow = black plastic (Hassell)
Effect of non-fumigant treatments on weed densities compared to MeBr
Treatment Rate kg/ha Total Weed Density
Untreated Control 69.9 a
Methyl Bromide 392 12.8 b
Steam 70 C for 20 minutes 7.8 b
Mustard Meal 2242 58.1 a
Fludioxonil + Mefenoxam + oxyflurofen
0.28 + 0.56 + 0.56 6.9 b
Mefenoxam + Thiophanate-methyl + oxyflurofen
0.56 + 1.57 + 0.56 8.5 b
Pre-Plant Burn Down Herbicides for Strawberries
Herbicide Weeds Controlled Rate/Acre Comments
Goaltender 2XL Many annual broadleaf weeds.
1-2 pt Must be applied at least 30 days prior to transplanting. The soil must be worked to a depth of at least 2.5 inches prior to transplanting the crop. No control is provided after the crop is planted.
RoundUp Ultra Most emerged weeds 1-5 qt Must be applied to emerged weeds at least 30 days prior to transplanting. For annual weeds, good soil preparation will also control these weed species
Aim EC Most small-mediumemerged weeds
2 oz Apply alone or with other herbicides or fertilizers as a burndown treatment at least 24 hours before transplanting.
Preplant Residual HerbicidesHerbicide Weeds Controlled Rate/Acre Comments
(pendimethalin)Prowl H20Satellite Hydrocap
Annual Grasses and small seeded broadleaf weeds
1.5-3 pt Prowl: Use before planting strawberries. Apply to the soil surface before planting to prevent the establishment of most annual grasses as well as suppressing several broadleaf weeds such as velvetleaf and purslane. Moisture is required to activate the herbicide, and it can be applied through an overhead irrigation system or shallowly incorporated. At least one day must elapse between application and planting, unless protective gear is worn. Only the H2O formulation of Prowl is labeled for strawberries. No more than 6 pints are to be used in any one season. Prowl H2O should not be used if plastic mulch will be applied.
(sulfentrazone)Spartan 4F
Annual broadleaf weeds 4-8 oz- most of SC soils would be closes to 4.
Apply prior to planting or just after planting but before new growth appears. May cause severe damage to new growth. Strawberry varieties vary in sensitivity. Provides control of many broadleaf weeds, including field pansy, groundsel and nutsedge.
Pre-herbicides applied at or after planting
Herbicide Weeds Controlled Rate/Acre Comments
Devrinol Annual grasses and small seeded broadleaf weeds
2 - 4 lb2 gal8 lb
(Formulation Dependent)
Apply to weed-free soil after strawberry plants become established. Heavy rate after planting may inhibit rooting of daughter plants. This material must be activated with rainfall, irrigation, or shallow cultivation within 24 hrs.
Prowl Annual grasses and small seeded broadleaf weeds
1.5-3.0 pt Banded Application (between rows) if applied at or after transplanting
Chateau Broadleaf weeds, some grasses, and some suppression of perennial weeds
3 oz Apply as a banded spray with a hooded or shielded sprayer to row middles or between plastic. Do not contact the strawberry plants including daughter plants. Apply prior to weed emergence
Herbicide Weeds Controlled Rate/Acre Comments
Dacthal FDacthal 75W
Annual grasses and small seeded broadleaf weeds
8 - 12 pt8 - 12 lb
Weak on ragweed, smartweed, and galinsoga. Apply at transplanting or after cultivating. Irrigation, rainfall, or shallow cultivation after application will improve control.
Sinbar 80WP Broadleaf weeds, some grasses, and some suppression of perennial weeds
2 - 6 oz During the planting year, Sinbar may be applied at 2 to 3 ounces per acre after transplanting but before new runners start to root. If strawberry plants have developed any new foliage prior to application, irrigation or rainfall (0.5 to 1 inch) is required to wash the Sinbaroff the strawberry plants. or soils with at least 2% organic matter, there is no maximum amount per application; however, no more than 8 ounces of Sinbar can be applied per year. For soils with between 1 and 2% organic matter, a maximum of 4 ounces of Sinbar can be applied at any one time with an annual maximum of 8 ounces per acre.
POST HerbicidesHerbicide Weeds Controlled Rate/Acre Comments
(paraquat)*GramoxoneSL 2.0
Emerged annual grasses and broadleaf weeds.Suppression of emerged perennial weeds between rows.
2 pt
Contact herbicide. Use with a non-ionic surfactant. Direct spray between rows using a shield to prevent contact with strawberry plants. Do not apply within 21 days before harvest or more than 3 times in a season.
(clopyralid)Stinger
Selected emerged broadleaf weeds including dandelion, Canada thistle, clover, vetch, ragweed, and jimsonweed
2/3 pt
Make one application per crop year after harvest to emerged weeds. Apply uniformly with ground equipment in a minimum of 10 gallons of water per acre. Do not tank mix with any other herbicides. Only this clopyralid product is registered for strawberry, other similar products with other trade names are NOT registered in New England. Do not use any spray additives.
Select grasses 6-8 oz Effective on small, actively growing grasses. Improved activity over Poast on cool-season and perennial grasses. Add 1qt/100 gal spray of crop oil concentrate. Repeat application at 14 days for perennial grasses. Ammonium sulfate at 2.5 lb/acre may be added to improve activity on perennial grasses. Do not apply within 4 days of harvest.
18% v/v Suppress in water carrier pH of 2.82
Untreated Check
18% v/v Suppress in water carrier pH of 2.82
Untreated
Suppress Organic Herbicide
2,4 D application in Row Middles
• Use Ai nozzles if possible.
Alternative Row Middle Management
Ryegrass in row middles. Terminate with Select
Spider mites – biocontrol
Eating adult Eating egg
Mites live in weeds!
Mites live in weeds!
How could weed management impact spider mite biological control?
Weeds promote spider mites
But weeds are good for natural enemies!
Shelter
Alternative prey
This includes phytoseiids
So what happens when weeds are managed?
So what happens when weeds are managed?
Harmful effects of the herbicide?
No shelterNo floral resourcesNo alternative prey
Spider mites seek out new food
Are the predators still alive to follow?
Herbicide, Abiotic Stress or injury from a biological?
Credit Ontario Ministry of Agriculture
Chateau Drift
Nitrogen Deficiency
Photo courtesy of University of California
Pursuit Injury
Sinbar
Magnesium Deficieny
Magnesium Deficiency
Photo: Scot Nelson/Flickr)
Gramoxone
Mite Damage
Crabgrass Control
Control Method- Select or Poast
Mice in Strawberry
Lavender and Cats
Questions