herbicides contact vs. residual selective vs. non...

1

Blueberry Weed Control: What’s Working for Michigan Growers

Mark Longstroth

Small Fruit Extension Educator Michigan State University Extension

Why Control Weeds in Blueberries?

Weeds compete with the crop:

water

nutrients

Alternate host for insect pests.

Interfere with pollination.

Reduce harvest efficiency.

Chemical Weed Control

Herbicides

• Contact vs. Residual

• Selective vs. Non-selective

• Pre vs. Post emergent

Contact Herbicides

Herbicide Activity

Poast grasses

Select grasses

AIM broadleaves, grasses, burndown

Gramoxone broadleaves, grasses, burndown

Roundup broadleaves, grasses, perennials

Rely broadleaves, grasses, burndown

Stinger broadleaves, some perennials

Contact Herbicides

Annuals Perennials

Herbicide Gr. BLW Gr. BLW

Non-selective herbicides – Avoid Green tissue

AIM G G P P

Gramoxone G G P P

Glyphosate G G G G

Rely G G F F

Aim (Carfentrazone)

Aim is a postemergence contact herbicide for quick burndown of small broadleaf weeds. It is most effective when used in tank mixes with residual herbicides or other postemergence herbicides. It can be applied anytime during the season, with a short or no PHI. It is most effective against common lambsquarters, pigweeds, morning glory, nightshades and velvetleaf. It is not effective against weeds larger than 6 inches.

Carfentrazone will kill new shoots but is not translocated in the plant.

2

Gramoxone (Paraquat)

Paraquat (Gramoxone) provides very rapid desiccation of annual and perennial weeds and may be utilized in all fruit plantings. Apply when weeds and grasses are succulent and new growth is 1 to 6 inches high. It has no preemergence activity if applied alone, and new weeds will emerge 5 to 10 days after application. Do not allow paraquat to contact foliage or green shoots. Paraquat may be combined with soil-active herbicides to provide season long weed control.

Gramoxone (Paraquat)

Roundup, and others (Glyphosate)

Glyphosate (many brands) controls both annual and perennial weeds. It is translocated in perennial plants and kills the underground parts. This makes it an excellent herbicide for control of quackgrass, Canada thistle, field bindweed and many other perennial weeds. Glyphosate has no preemergence activity. Glyphosate can seriously injure plants if it contacts green leaves, shoots, or wounds. Application on young canes of blueberry can reduce plant vigor and new cane production.

Notes on Glyphosate

Glyphosate may be combined with preemergence herbicides to provide season long weed control. Apply in a maximum of 20 gal of water per acre. Ammonium sulfate increases Roundup efficacy on a broad spectrum of weeds when spraying with hard water. Add 17 lb. of ammonium sulfate per 100 gal of spray solution before adding the glyphosate.

Glyphosate Rely (Glufosinate)

Glufosinate (Rely 280) is a foliar-active, nonselective herbicide that controls a broad spectrum of emerged annual and perennial weeds. Best results are obtained when it is applied to actively growing weeds. Glufosinate does not provide residual weed control but can be tank mixed with residual herbicides for broad-spectrum control.

Avoid contact with green bark and foliage.

Do not apply within 14 days of harvest.

3

Contact Herbicides

Annuals Perennials


Selective Grass Herbicides

Poast G P G P

Select G P G P

Fusilade*** G P G P

Selective Broadleaf Herbicide

Stinger P G P P/E

Fusilade DX (Fluazifop-P)

Fluazifop-P (Fusilade DX) is a postemergence grass herbicide. Apply to actively growing grasses before they exceed the growth stage specified on product label (annual grasses less than 8 inches tall and actively growing perennial grasses with 8 to 10 inches of new growth). Fusilade at higher rates is quite effective against quackgrass. Avoid spray contact with foliage.

Poast (Sethoxydim)

Sethoxydim (Poast) is a postemergence grass herbicide. Most grasses are controlled with 1 to 2 pints per acre. It does not control broadleaves. Add crop oil concentrate (COC) or nonionic surfactant (NIS) to the spray solution. Should be applied during active growth (annual grasses less than 8 inches tall and actively growing perennial grasses with 8 to 10 inches of new growth).

Stinger (clopyralid)

It is very active against all members of the Asteraceae family (composite weeds), including Canada thistle, burdock, dandelion, common groundsel, marestail, mayweed, goldenrod and ragweeds. It also controls legumes (alfalfa, clover, trefoil, vetch), nightshades and plantains. It suppresses most members of the Polygonaceae family, including smartweeds, knotweeds, red sorrel, curled dock and wild buckwheat. It will suppress wild carrot.

Controls: asters, clover, dandelion, goldenrod, smartweed,

thistles, ragweed, red sorrel, vetch, wild bean, wild buckwheat

Stinger (clopyralid) Post-emergent with some pre-emergent activity

Rates:

2.7 to 5.3 fl oz/acre, not more than 10.6 oz. per year Timing:

do not apply from 1 week before and after bloom.

PHI 30 days Can be applied after harvest

Stinger Injury in Blueberry

4

Residual Grass Herbicides

Annuals Perennials


Devrinol** G P P P

Kerb G P G P

Prowl*** G P P P

Surflan** G P P P

Solicam G F F P

Devrinol (Napropamide)

Napropamide (Devrinol) can be applied at 4 lb/acre in newly planted or established blueberry plantings for annual grass and broadleaf weed control. Apply to weed-free ground. Napropamide is inactivated by light and is most effective if incorporated into soil by tillage, irrigation or rainfall following application. Napropamide does not control established weeds.

Kerb (Pronamide)

Pronamide (Kerb) is effective in suppressing quackgrass and annual grasses. It also controls some annual broadleaves. Apply in November before soil freezes. It is not very effective on soils with high

organic matter content.

Surflan (Oryzalin)

Oryzalin (Surflan) can be used safely on newly planted blueberries after the soil has settled and no cracks are present. It is a preemergence herbicide, effective in controlling annual grasses and some annual broadleaved weeds. It has little effect on established weeds. Combine with diuron, simazine or terbacil for broad-spectrum, season long control. One-half inch of rain or sprinkler irrigation is needed to activate the herbicide.

Solicam (Norflurazon)

Norflurazon (Solicam) is a preemergence grass herbicide that gives some control of a few broadleaves. It gives good suppression of yellow nutsedge if applied in the fall. Rainfall is necessary to move Solicam into the weed root zone for the chemical to be effective. Combinations with diuron or simazine provide broad-spectrum weed control.. Injury may appear as veinal chlorosis.

Solicam (Norflurazon)

5

Residual Broadleaf Weed Herbicides

Annuals Perennials


Karmex P/F G P P

Princep P/F G P P

Sinbar F G P P

Chateau P/F G P P

Callisto F G P G

Velpar F G P G

Matrix G F P P

Karmex (Diuron)

Diuron (Karmex) is effective on annual grasses and broadleaved weeds. Applied at 3 to 4 lb/acre in the spring, it provides acceptable weed control for 8 to 10 weeks. Delaying application until early May and including glyphosate in the tank mix extends weed control into the harvest season. Diuron can also be tank mixed with other soil-active herbicides for improved control of a wider range of weed species.

• Mode of action: PSII inhibitor

Karmex (Diuron) Princep (Simazine)

Simazine (Princep) is effective primarily on germinating annual weeds but does provide some quackgrass suppression when applied in the spring in combination with paraquat or glyphosate. Use lower rates on light soils. Injury may occur on light sandy soils when the rate of application exceeds 2 lb/acre. Simazine normally does not build up in the soil from annual application of labeled rates. Injury may appear as interveinal chlorosis.

• Mode of action: PSII inhibitor.

Princep (Simazine) Sinbar (Terbacil)

Terbacil (Sinbar) controls most annual weeds and also suppresses some perennial weeds. Spring applications of Sinbar at 0.5-1 lb. per acre will control most annual weeds. Two to 3 lb/acre are needed to control quackgrass and yellow nutsedge. Sinbar is very soluble and may leach downward in very sandy soils. Injury, appearing as yellow leaves, may result from applying too much chemical on light soils. To avoid crop injury on sandy soils, always use the lowest labeled rate and do not apply every year. Mode of action: PSII inhibitor.

6

Sinbar (Terbacil) Casoron (Dichlobenil)

Dichlobenil (Casoron) controls quackgrass, yellow nutsedge and other perennials in established fruit plantings. It is currently sold as a granular formulation. It is most effective if applied in November. Four pounds of active ingredient (100 lb. of 4 G or 2.8 gal of 1.4 CS) per acre will control most perennials until midsummer of the following

year.

Chateau (Flumioxazin)

Registered in blueberries for preemergence weed control. It gives good long-term control of several difficult weeds, including lambsquarters, mustards, nightshades, morning glory and pigweeds. It is weak on marestail. It has become popular with Michigan growers as a new mode of action for herbicide resistant weeds. It is tank mixed with glyphosate or paraquat for emerged weed suppression. Avoid contact with green bark, foliage and new shoots. Ten to 12 weeks’ residual activity.

CHATEAU WDG (flumioxazin)

Preemergent (some postemergence activity with COC or NIS).

Apply early spring to early summer (PHI 7 days) or late fall.

Bushes 3 years or older

6 to 12 oz. Use lower rates on sandy soils

Controls: annual grasses, chickweed, dandelion, groundsel,

lambsquarters, marestail(?), nightshade, pigweed,

smartweed (post)

Callisto (Mesotrione)

Mesotrione (Callisto) has both preemergence and postemergence activity on most broadleaves and large crabgrass. It does not control most other annual grasses and common purslane. Combining it with another preemergence herbicide should give very broad and effective weed control. Callisto has a new mode of action (HPPD inhibitor), which causes green leaves to turn white. Some leaves of crop plants may turn white after application, but no permanent damage is done to the plants.

Callisto (Mesotrione)

7

Velpar (Hexazinone)

Hexazinone (Velpar) is labeled for control many herbaceous and woody plants. Use Velpar primarily for woody perennials. It controls or suppresses briars, brambles and wild cherry. Apply 1 to 2 lb. in the spring before blueberry plants begin active bud development. Velpar is very soluble and may leach into root zone on light soils. Do not apply on soils that are 85 percent or more sand. Do not apply to blueberries less than 5 years old, and do not repeat applications in successive years.

• Mode of action: PSII inhibitor

Velpar (Hexazinone)

Velpar (Hexazinone) Zeus (Sulfentrazone)

Sulfentrazone (Zeus) is a PPO inhibitor with preemergence and postemergence activity on many annual broadleaves, grasses, and sedges, including yellow nutsedge. It is especially effective against amaranths and pigweeds, and can be used for resistance management in all Amaranthaceae species. It is a good tank mix partner with the Photosystem II (PS II) inhibitors Sinbar, Karmex and Princep. Sulfentrazone should be used on established plantings (3 + years in field).

The PHI for most crops is 3 days.

Sandea (halosulfuron)

Sandea has become very popular in blueberries where

yellow nutsedge is a problem weed. It has no grass

activity. It is most effective for yellow nutsedge control

at the 4-6 inch stage and is often used as a post

emergent spray. Two applications should control

nutsedge for most of the season.

For most effective weed control, use Sandea in

combination with a PSII inhibitor or a PPO inhibitor.

Matrix (rimsulfuron)

Rimsulfuron may be applied preemergence to the soil in blueberries and cane fruit. It will provide control of most broadleaves and grasses. It is most effective if used in a tank mix with a PSII inhibitor such as diuron or simazine and a burndown herbicide such as glyphosate.

Same mode of action as Sandea; do not use these together in the same year.

8

Herbicide Modes of Action Herbicide Mode of Action

Karmex, Princep, Sinbar, Velpar Inhibit photosystem II

Casoron Inhibit cellulose synthesis

Sandea, Matrix ALS inhibitor

Solicam Disrupt carotenoid synthesis

Stinger Auxin growth regulator

Surflan Inhibit microtubules (cell division)

Devrinol, Dual Magnum, Kerb Inhibit VLCFAs (cell division)

Callisto HPPD inhibitor (pigments)

Aim, Chateau, Zeus PPO inhibitor (disrupts

membranes)

Herbicide combinations

The continuous use of herbicides over many years may result in development of weed resistance to herbicides with that mode of action. Diuron, simazine and terbacil all have the same mode of action, and their continuous use alone or in combination will exacerbate the potential for herbicide resistance. To avoid buildup of resistant weeds, use herbicide combinations that include other modes of action.


Some potential combinations of residual herbicides are: Karmex or Princep or Sinbar (all PSII inhibitors) plus Chateau (PPO inhibitor); or Casoron, Kerb or Solicam in the fall, followed by a PSII inhibitor in the spring; or Surflan plus a PSII inhibitor or PPO inhibitor in the spring. Anytime emerged weeds are present, include a postemergence foliar herbicide.


Anytime emerged weeds are present, include a postemergence foliar herbicide, such as Aim, Gramoxone, Rely or Roundup. Use a postemergence grass herbicide if your only target weed is emerged grasses. Use Stinger if your primary objective is composite and legume weeds (e.g., marestail, dandelion, goldenrod, clover). By using combinations such as these, growers should be able to maintain almost weed-free soil in the rows.

Blueberry Weed Control Recommendations for 2015

• Use 2 herbicides preemergence (PRE) with different modes of action before bud break

• Include a foliar-active herbicide in the PRE treatment: Gramoxone, Rely, Roundup, Aim

• Apply another PRE herbicide during the season, eg. Sandea (14 d PHI), Chateau (7 d PHI), Dual Magnum (28 d PHI), Matrix (21 d PHI), Zeus XC

• Include a POST herbicide, e.g., Rely 280 (14 d PHI), Stinger (30 d PHI), Aim (0 d PHI)

Multiple Herbicide Applications

Many grower apply herbicides in the spring and hope for season long control. Few materials give season long control at safe rates.

Applying herbicide combinations in the spring and in the fall allows good season long control.

This technique is especially useful on lighter soils

9

Using Herbicides and Mulches

Organic Mulches complicate herbicide applications because the mulch will absorb most of the herbicide.

Rates should be increased and focus should be on problem weeds in the mulch.

A thick organic mulch will suppress weeds emergence from under the mulch.

Annual weeds rooting in the mulch surface are the major problem.

Using Herbicides and Mulches

Plastic Mulches complicate herbicide applications because the mulch sheds the herbicide off the plastic and concentrates it at the edges of the mulch.

Herbicide applications should be directed at the edge of the plastic, letting the plastic mulch will suppress weeds emergence from under the mulch.

Spot treatment with grass herbicide

April May June July

Budswell Petal fall Green fruit Dormant Bloom

(early spring or late fall) Casoron

Chateau (7 d PHI)

Princep (before fruit are present)

Matrix (21 d PHI)

Sandea (14 d PHI)

Solicam (60 d PHI)

Callisto (before bloom)

Dual (28 d PHI)

Stinger (not 1 week before

or after bloom) Stinger (30 d PHI)

Glyphosate, Ignite (14 d PHI)

Poast (30 d PHI)

Aim (0 d PHI)

Gramoxone (before new shoots emerge)

(before bud break) Velpar

Weed Control Failures

• Perennial Weeds

• Poor Integration of Control Options

• The Wrong Herbicide

• The Wrong Rate

• Poor Application Technique

• Inappropriate Application Timing

• Bad Luck – Weather Problems

Questions?

I would like to acknowledge,

Dr. Eric Hanson and

Dr. Bernie Zandstra

herbicides contact vs. residual selective vs. non...

Documents