PISTACHIO WEED MANAGEMENT

Transcription

1 PISTACHIO WEED MANAGEMENT 2008 Pistachio Production Short Course Visalia, CA Kurt Hembree Farm Advisor, Fresno County

2 DISCLAIMER No single herbicide or program will give seasonlong control of all weeds in pistachio orchards. The best we can hope to achieve is good weed management.

3 Tree age should affect the way weed management decisions are made. Before Planting - Are there any perennial weeds? - Are there any hard-to-kill annuals? - Land prep and apply preplant herbicide Non-Bearing Years - Set a goal to eliminate weed competition - Apply pre and postemergent herbicides - Avoid tree injury from herbicides and equipment Bearing Years - Management phase - Herbicide rotation, tank-mixing, change as needed

4 Most growers do a good job of managing weeds once the orchard is well established.

5 Controlling weeds up thru the non-bearing years can be difficult and costly, but is necessary for easier management later.

6 Before Planting Perennials are troublemakers! Bermudagrass Dallisgrass Dandelion Field bindweed Johnsongrass Nutsedge, purple Nutsedge, yellow

7 Dr. Theodore M. Webster (USDA-ARS, Tifton, GA)

8 Deep burial of yellow nutsedge with a Kverneland plow before cotton Prather et al. 2003

9 Field bindweed control with a high rate of glyphosate, then undercutting can buy time. 7/22/03 RU, 4 lb ai/a, NIS, 15 gpa 7/29/03 - Undercut 1 year later RU + UC UC

10 Consider which annuals you ll be up against! Winter Annuals Summer Annuals Annual bluegrass Hairy fleabane* Cheeseweed Horseweed* Chickweed Knotweed Filaree Lambsquarters Groundsel Large crabgrass Henbit Mullein London rocket Pigweed Nettle Purslane Prickly lettuce Russian thistle Shepherd s-purse Sowthistle Willowherb Spurge

11 Life-cycle of horseweed and hairy fleabane in California Spring emergence (horseweed) Spring emergence (hairy fleabane) Fall emergence (horseweed) Fall emergence (hairy fleabane) Flower Seed dispersal Flower Seed dispersal Winter survival Spring emergence Bolting Fall emergence Winter survival Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

12 Start off as clean as possible! It s not perfect, but will help keep you ahead of the curve. 1 gal Prowl used preplant will help reduce the population of grasses and some broadleaves. Annual grasses Annual broadleaves Annual bluegrass Chickweed Barnyardgrass Fiddleneck Bermudagrass (seed) Goosefoot Bromegrass Henbit Crabgrass Knotweed Dallisgrass (seed) Lambsquarters Foxtails Pigweed Johnsongrass (seed) Purslane Ryegrass, Italian

13 Non-Bearing Years Slow canopy development means more sunlight reaching the soil and more weeds to deal with.

14 Young trees are very sensitive to competition from weeds. Rodents can also reap havoc where grassy weeds and nutsedge are growing.

15 Some weeds are good hosts to economic insect pests, including False chinch bug Knotweed, Spurge, London rocket Lygus Russian thistle, Burclover, Birdsfoot trefoil, Lambsquarters, Redroot pigweed Green plant bug Sunflower, Russian thistle Green soldier bug Black mustard, Nightshade

16 Plan herbicide use ahead of time

17 For a list of herbicides used in pistachios, rates and timings, and major weeds controlled Pistachio Production Manual (Label)

18 Young trees are sensitive to postemergent herbicides. For example, paraquat damage can inhibit rootstock growth, harden off bark, and make budding in July/August difficult.

19 Preemergent herbicides in non-bearing orchards ±1 yr Label NB 1 yr NB Chateau Devrinol Gallery Goal Matrix Prowl Surflan Visor Cheeseweed Chickweed Common purslane Filaree Hairy fleabane Henbit Horseweed Knotweed Mullein Nettle Panicle willowherb Prickly lettuce Puncturevine Russian thistle Bermudagrass (s) Yellow nutsedge

20 Some key things to consider when comparing preemergents Herbicide Time to incorporate Minimum rainfall Devrinol 4-10 days ¼ Matrix FNV 21 days ½ Gallery T&V 21 days ½ Surflan 21 days ½ Visor 21 days ½ Prowl H 2 O Prowl 3.3 EC 21 days 7 days (mechanically) ½ -- Chateau 28 days ¼ Goal 28 days ¼ *Cooler conditions favor time before rainfall

21 Some key things to consider when Herbicide Min. GPA Affected by soil trash Affected by disturbance Chemigate Devrinol 20 YES NO YES* Matrix FNV 20?? YES* Gallery T&V 20 yes NO NO Surflan 20 yes NO YES* Visor 20 NO NO NO Prowl H 2 O Prowl 3.3 EC comparing preemergents yes NO NO NO YES* YES* Chateau 30 YES YES NO Goal 30 YES YES YES* *Don t contact foliage!

22 A good preemergent program for a large number of annual broadleaf weeds Oct-Dec: Matrix FNV (4 oz) + Prowl H 2 O (5 pt) ± Postemergent(s) then Jan-Mar: Chateau (12 oz) + Prowl H 2 O (5 pt) ± Postemergent(s) If you want to save your preemergents for late winter, then Oct-Dec: Postemergents (2,4-D amine, RU, Rely, etc.) need to go on young weeds (no bigger than a silver dollar) then Jan-Mar: Chateau (12 oz) + Prowl H 2 O (5 pt) ± postemergent(s) or Matrix FNV (4 oz)

23 If yellow nutsedge is also an issue Oct-Nov: Visor (2 pt) + Chateau (12 oz) ± Postemergent(s) then Dec-Jan: Visor (2 pt) + Matrix (4 oz) ± Postemergent(s)

24 If the weeds have seeded, preemergents are needed Hembree, 2008

25 Postemergent herbicides in non-bearing orchards NB NB 1 yr Fusil Gramo Poast Rely Round Select Shark Venue 2,4-D Cheeseweed Chickweed Common purslane Filaree Hairy fleabane Henbit Horseweed Junglerice Knotweed Mullein Nettle Prickly lettuce Puncturevine Russian thistle Bermudagrass Yellow nutsedge

26 Some key things to consider before using postemergents Treatment timing Coverage Spray volume Weed spectrum (resistance or shift) Drift or contact with green wood or foliage Adjuvants and additives Cost-effectiveness

27 Postemergents require early timing!

28 Postemergents require early timing!

29 Tank-mixing can sometimes makeup for spraying late, sometimes.

30 Horseweed treated too late with glyphosate Vetch treated too late with paraquat

31 Are the nozzles you re using giving good enough spray coverage? TwinJet Off-center or Flat fan

32 Hairy fleabane nozzle type comparison Untreated Rely.75 + RU 2 FF 20 psi 42 gpa Rely RU 2 FF 20 psi 42 gpa Rely.75 + RU 2 TJ 45 psi, 45 gpa Rely RU 2 TJ 45 psi, 45 gpa

33 Contacts require complete coverage! Before treatment

34 Rely at 1 gal/acre XR8004, 30 psi, 26 gpa 14 DAT

35 Rely at 1 gal/acre XR8008, 30 psi, 52 gpa 14 DAT

36 Tank-mixing often increases the spectrum of control and reduces or delays weed resistance and weed shifts.

37 30 DAT Roundup Gramoxone Rely Venue

38 30 DAT Gramoxone + Venue Roundup + Venue Roundup + Rely Untreated

39 Organic herbicide options are expensive and limited in effectiveness Acetic acid applied 3X

40 Matran EC EMULSIFIABLE CONCENTRATE NO REENTRY INTERVAL Ingredients in this product meet the requirements of the USDA National Organic Program Active Ingredients: Clove Leaf Oil % Other Ingredients* % Total % *Wintergreen Oil, Butyl Lactate, and Lecithin Mustard Control at 35 GPA Lanini, UC Davis

41 For Control of Annual and Broadleaf Weeds In Non-Crop Areas ACTIVE INGREDIENT: d-limonene 70% INERT INGREDIENTS: % Total...100% KEEP OUT OF REACH OF CHILDREN CAUTION Lanini, UC Davis 35 GPA 0.25% v/v Natural Wet

42 Reducing weed populations and seed bank reserves in the first 6 years or so can open up other avenues for controlling weeds that may be more economical.

43 Weed Seeker ( smart sprayer technology) *Practical where weeds are spotty or patchy

44 Dr. Tim Prather, UC KAC 1999 Assume: Pistachio orchard, GLY, 25 gpa, 2% v/v, 19 row space, 6 strip, then: 100% 20% 5% 20.2 oz/a ~4 oz/a ~1 oz/a

45 Smart use of pre- and postemergent options during the non-bearing years can help do several things: Give the trees as good a growth opportunity as possible for the bearing years Allow for increased flexibility in herbicide selection and use Limit the weed population to allow for easier management through the life of the orchard

46 Bearing Years Practice good herbicide selection (tank-mixes) and rotation to keep the weeds off balance. Increase efficiencies by fine-tuning things like, nozzle selection, coverage, spray volume, leaf debris, treatment timing, etc. Spend time monitoring fields for escapes and shifts and adjust program accordingly. Keep weeds from producing additional seed.

47 SUMMARY Apply a preplant (Prowl) to reduce initial weed pressure. Use good preemergent combinations during the nonbearing years to reduce the weed population, making postemergent sprays more practical. Don t treat the leaves, treat the soil. When using postemergents; treat early, keep the volume up, cover the weeds, tank-mix, and keep it off the trees. Once weeds are under control early, it will free up more time needed for other more pressing tasks (hunting, fishing, skiing, etc.)

48