POSTEMERGENT WEED CONTROL AND LABEL UPDATES IN ALMONDS

2008 North San Joaquin Valley Almond DayJanuary 22, 2008

Kurt HembreeUCCE, Fresno County

Treatment lb ai/A 15 DAT 30 DAT 15 DAT 30 DAT 15 DAT 30 DAT 1. Roundup1,2 2 7.5 4.7 9.7 8.6 10 9.9

2. Gramoxone1,2 0.75 9.6 9 9.1 8.5 10 9.5

3. Rely1 1 9.9 9.8 9 6 10 9

4. Venue1,2 .0028 7.5 6.1 2 0 0 0

5. ACB D331,2 .045 9.9 9.9 1 0 1 0

6. Scythe1 13 8.8 5.3 5.3 2 5 3

7. Roundup+Venue1,2 2 + .0028

8.8 7.5 8.2 7.5 9.9 9.7

8. Roundup+ACB D331,2 2 + .045 10 9.9 9 8 10 9.5

9. Roundup+Chateau1,2 2 + .125 8.7 6 9.7 9.3 10 9.8

10. Roundup+Scythe 2 + 4 8.8 5 9.4 6 9.8 8.5

11. Rely+Venue1,2 1 + .0028

9.9 9.9 9.6 6.5 10 9.7

12. Rely+ACB D331,2 1 + .045 10 9.9 9.6 8.5 10 9.7

13. Rely+Chateau1,2 1 + .125 10 9.9 9.5 8 10 9.8

Postemergent Weed Control Trial in AlmondsFresno County - 2007

*Horseweed (8 leaves - bolted), yellow nutsedge (2-6 leaves), crabgrass (2-4 leaves) Spray volume at 40 gpa, 1AMS added at 8 lb/100 gal, 2Agridex at 1% v/v

Horseweed* Y. Nutsedge* Crabgrass*

4/2/07 – day of application

5/6/07 – 30 DAT

Roundup Gramoxone

Rely Venue

ACB D33 Scythe

5/6/07 – 30 DAT

5/6/07 – 30 DAT

Roundup + Venue Roundup + ACB D33

Roundup + Chateau Roundup + Scythe

5/6/07 – 30 DAT

Rely + Venue Rely + ACB D33

Rely + Chateau Untreated

Postemergence control of horseweed and hairy fleabane across 4 trials in 2007

0

2

4

6

8

10

RU GR RL ACB SK VU RU +VU

RU +ACB

RU +CH

RU +SK

RL +VU

RL +ACB

RL +CH

Con

trol

Horseweed Fleabane

Summary of Postemergent Treatments Since 2005:

• Rely applied alone seems to give the most consistent control of horseweed, fleabane and other broadleaves, but is somewhat weak on grasses and sedges. Adding other contacts improves control slightly. With the recent price drop of Rely, tank-mixing Rely and Roundup may be the way to go for the most consistent control.

• The PPO herbicides (Shark, Venue, Chateau) should not be used alone, unless you only have annual broadleaves, and they are very, very small. Gramoxone usually gives equal to better control. Success with the PPO products seems to be related to weather conditions.

• Keeping the spray volume up with complete coverage is important.

• ACB D 33 gave exceptional control of horseweed and fleabane when used alone or mixed with Roundup or Rely.

Herbicide Label Updates and Improving Product Performance:

• Chateau SW (Valent)• Matrix FNV (DuPont)

Stanislaus County - May 2007

Roger Duncan

Early signs of wilt Shoot dieback

Dieback withmottled leaves

Roger Duncan

Technical bulletin added to the label in Oct 2007 for Merced, Stanislaus,

and San Joaquin Counties

Improving preemergent performanceof Chateau:

• A clean soil surface prior to application maximizes control.

• Apply in a spray volume of no less than 30 gpa.

• Using 12 oz in the fall mixed with Prowl H20 or other preemergent will help broaden the control and get the “toughest” flush of horseweed and fleabane. If horseweed or fleabane are emerged at that time, adding 2,4-D or other contact should do the job, making spring weed control much easier.

• Where purslane is a problem, a second application or delaying application to just before petal fall can extend control later.

• Don’t expose tree roots to direct contact with the herbicide. If replanting into treated areas, use clean soil around roots.

Matrix FNV Application Info.• Tree age: 1 year

• Timing: preemergence is it’s strength (2-3 months)

• Soil surface: free of trash

• Rate: 4 oz/A/year (broadcast), split-application allowed (2 oz + 2 oz) if banded and <50% area treated

• Spray volume: 30-50 gpa

• Spray Tank pH: 5 - 7

• Activation: ½ inch rainfall ≈14 days. (apply to moist soil)

• Chemigation: through micro-sprinklers only

• Tank-mix partners: other preemergents (Prowl H20); permit if GWPA regulated product is added; postemergents (RU, Gramoxone, Rely, etc.)

• Tree injury: likely if under poorly drained conditions and direct root contact?

Weeds controlled preemergence with Matrix FNV:

Annual Broadleaves:Dandelion (seedling)FilareeGroundselHenbitMallowMustardsShepherd’s-purseFleabaneHorseweedPigweedsPurslanePuncturevineSpurge

Lambsquarters*Nightshades*Velvetleaf*

Annual Grasses:BarnyardgrassCrabgrassFoxtails (yellow, green, giant)Volunteer cereals*

Perennials:Yellow nutsedge*Field bindweed*Johnsongrass*

*Suppression