Pumpkin Weed Management: Options & Economics

Nathan JohanningExtension Educator, Local Food Systems and Small FarmsUniversity of Illinois ExtensionMurphysboro, Illinois

The Importance of Weed Management• Weed/Pumpkin plant competition can

severely reduce yields• Weeds can limit air movement

• Increase the incidence of some plant diseases

• Weeds can harbor insects• Reduce/interfere with spray coverage of

pesticide applications

Problematic Weeds in Pumpkins

• Amaranthus spp. • Waterhemp, pigweeds, palmer amaranth

• Morningglories• Hophornbeam Copperleaf• Common/giant ragweed• Crabgrass• Foxtail spp.• Volunteer small grains

Common Management Methods• Herbicides• Cover Crops/No-Till• Tillage/Cultivation• Crop Rotation• Hand weeding/hoeing• Spot/directed herbicide applications

Common Herbicides • Gramoxone SL• Roundup PowerMax• **Reflex** (NEW)• Dual Magnum• Strategy• Command (processing only)• Sandea• Select Max/Poast

• See the Midwest Vegetable Production Guide for full details• http://www.btny.purdue.edu/pubs/id/id-56/

Herbicide Resistant Weeds

Species ALS

Inhi

bito

rs (B

/2)

EPS

P sy

ntha

ses i

nhib

itors

(G/9

)

Phot

osys

tem

II in

hibi

tors

(C1/

5)

PPO

inhi

bito

rs (E

/14)

ACCa

se in

hibi

tors

(A/1

)

Palmer Amaranth X XTall Waterhemp X X X XSmoth Pigweed X XHorseweed X XGiant Foxtail X XShattercane XEastern Black Nightshade XCommon Cocklebur XGiant Ragweed XCommon Ragweed X XKochia X XCommon Lambsquarters X

Herbicide Resistant Weeds in Illinois• Herbicide resistance is a becoming challenge to our weed management strategies• Waterhemp• Marestail (Horseweed)• Ragweed spp.

• Pay attention to the herbicide site of action(Listed in parentheses)

Considerations When Using Herbicides• Identify problematic weeds!• May have a potential for crop injury

• Make sure to follow labeled guidelines• Understand the risks of injury associated with the

individual herbicide; each is different• Potential carryover to future crops• Preemergence herbicides need rainfall to

“activate” or incorporation (tillage)• Generic Herbicides

• Can be equally effective (and more cost effective)• CHECK LABEL for different rates or adjuvant needs!

**Reflex** (14 )• Active Ingredient: fomesafen• Residual (some foliar activity)• Application Timing(s):

• Preemergence*• Notes:

• Newly labeled product in Illinois. Indemnified 24(C) Label REQUIRED*

• Excellent control of many small seeded broadleaves (waterhemp/pigweeds, purslane). Good control of common ragweed, nightshades and horsenettle

**Reflex** (14)

• This is an indemnified 24(C) Label requiring a waiver.• To get the label and waiver go to: www.farmassist.com

• Crop Protection> Labels> Indemnified Labels>

• Trials and field observations have shown good crop safety especially to most Jack O’Lantern varieties and to transplants.

• Some specialty varieties, especially when direct-seeded, may be at a greater risk of some crop injury.

Labeled Use of Reflex• Reflex Herbicide (or any other fomesafen

containing herbicide) may only be applied in ALTERNATE years in Illinois• Fomesafen is also found in the soybean herbicides

Flexstar, Prefix, and equivalent generics.

• Rate: 0.5 – 1 pt/A • Preemergence broadcast application after direct

seeding pumpkin, but before crop emergence OR

• Pre-transplant non-incorporated broadcast application up to 7 days prior to transplanting pumpkins.

Making Use of Reflex

• Reflex is not necessarily a good stand alone preemergence product but it can help enhance control of some of our problematic broadleaf weeds

• Partner it with some other PRE herbicides:• Dual Magnum• Sandea• Strategy

Dual Magnum or Dual II Magnum (15)• Active Ingredient: s-metolachlor• Residual only (no foliar activity)• Application Timing(s):

• Preemergence **(between rows only)

• Notes:• Good on grasses, small seeded broadleaves

(waterhemp) and nutsedge• Good crop safety

Dual Magnum 24c Label• Extened the indemnified 24c Label for Dual

Magnum in IL allowing PreemergenceBroadcast use broadcast on pumpkins (expires 12/22/2022)• You have to register at www.farmassist.com to

download this indemnified label and waiver for this use pattern

• “Apply Dual MAGNUM at a rate of 1.0 to 1.33 pints/A pre-emergence (before the weeds have emerged) to pumpkin. Use the lower Dual MAGNUM rate on soils light in texture (loamy sand or lighter) and low in soil organic matter (less than 3%). If Dual MAGNUM is applied as a broadcast spray over the planted row or hill, injury to the pumpkin crop can occur which may include stand loss, delayed maturity, and even loss of yield. Do not apply Dual MAGNUM after the pumpkin seedlings have emerged.”

Strategy (13 & 3)

• Active Ingredient: clomazone + ethalfluralin• Residual only • Application Timing(s):

• Preemergence

• Notes:• Good on grasses and select broadleaves

(velvetleaf, lambsquarter)

Sandea (2)• Active Ingredient: halosulfuron• Foliar and residual; systemic• Application Timing(s):

• Preemergence• Postemergence

• Either can cause crop injury especially POST

• Notes:• Good on broadleaves and excellent on nutsedge• Some weed resistance to this Site of Action

especially POST • Waterhemp, Marestail

SelectMax/Poast (1) • Active Ingredient: clethodim/sethoxydim• Selective, systemic; no residual• Application Timing(s):

• Postemergence• Notes:

• Good on all grasses only. Best results when grasses are small (4 inches or less).

• Make sure to note any adjuvant recommendations, especially on generics

• Select is generally better on perennial grasses than Poast

2016 Pumpkin Herbicide Trial• Ewing Demonstration Center, Ewing, IL• No-till into wheat stubble and the study area started

clean with a blanket application of Gramoxone 2 SL at 3 pt/A + COC 1% v/v

• Single replication plots• 12 feet wide (two rows) and 80 feet long

• Pumpkin ‘Magic Wand’ direct –seeded (left row) and transplanted (right row) June 24, 2016.

• Preemergence treatments applied June 24, 2016 (after seeding, before transplanting); Postemergence treatments applied August 4, 2016.

• All pricing information is based off of the average retail price (2016) from two retailers and should be used as a comparison between treatments rather than for negotiation of specific product pricing with your supplier

Trial Notes• The main weeds problematic weeds were

waterhemp (glyphosate resistant) and morningglories. Fairly low grass weed pressure

• We had an EXTREMELY wet growing season and lots of pressure on these herbicides to perform• June through end of August over 19” rain

• We did not observe any crop injury from any of the treatements.

2016 Herbicide TrialTrt Herbicide Product Rate Timing Estimated Cost ($/A)

1 Nontreated2 Reflex

Select MaxNon-ionic Surfactant

1 pt/A12 fl oz/A0.25% v/v

PREPOST - 4” GRASSPOST - 4” GRASS

$6.70$9.80$0.87

$17.37

3 ReflexSelectMaxNon-ionic Surfactant

0.5 pt/A12 fl oz/A0.25% v/v

PREPOST - 4” GRASSPOST - 4” GRASS

$3.35$9.80$0.87

$14.02

4 Dual MagnumSelect MaxNon-ionic Surfactant

1.33 pt/A12 fl oz/A0.25% v/v

PREPOST - 4” GRASSPOST - 4” GRASS

$19.18$9.80$0.87

$29.85

5 Dual MagnumReflex

1.33 pt/A1 pt/A

PREPRE

$19.18$6.70

$25.88

6 Dual MagnumReflexSelect MaxNon-ionic Surfactant

1.33 pt/A1 pt/A12 fl oz/A0.25% v/v

PREPREPOST - 4” GRASSPOST - 4” GRASS

$19.18$6.70$9.80$0.87

$36.55

2016 Herbicide Trial – cont’dTrt Herbicide Product Rate Timing Estimated Cost ($/A)

7 Dual MagnumSandeaSelect MaxNon-ionic Surfactant

1.33 pt/A0.75 oz/A12 fl oz/A0.25% v/v

PREPREPOST - 4” GRASSPOST - 4” GRASS

$19.18$38.44

$9.80$0.87

$68.29

8 Dual MagnumSandeaSelect MaxNon-ionic Surfactant

1.33 pt/A0.75 oz/A12 fl oz/A0.25% v/v

PRE4-5 leaf pumpkin4-5 leaf pumpkin4-5 leaf pumpkin

$19.18$38.44

$9.80$0.87

$68.29

9 Dual MagnumStrategySelect MaxNon-ionic Surfactant

1.33 pt/A6 pt/A12 fl oz/A0.25% v/v

PREPREPOST - 4” GRASSPOST - 4” GRASS

$19.18$74.63

$9.80$0.87

$104.48

10 StrategySelect MaxNon-ionic Surfactant

6 pt/A12 fl oz/A0.25% v/v

PREPOST - 4” GRASSPOST - 4” GRASS

$74.63$9.80$0.87

$85.30

Nontreated

Reflex 1 pt/A PRE + Select Max POST

$17.37/A

Reflex 0.5 pt/A PRE + Select Max POST

$14.02/A

Dual Magnum PRE + Select Max POST

$29.85/A

Dual Magnum + Reflex 1 pt/A PRE$25.88/A

** Dual Magnum + Reflex 1 pt/A PRE ** + Select Max POST

$36.55/A

Dual Magnum + Sandea PRE + Select Max POST

$68.29/A

Dual Magnum PRE + Sandea & Select Max POST

$68.29/A

Dual Magnum + Strategy PRE + Select Max POST

$104.48/A

Strategy PRE + Select Max POST

$85.30/A

Summary

• Reflex can be a good tool especially for waterhemp control.• Use with Dual Magnum and/or Sandea, or Strategy

• Strategy does help more with some grasses and selected broadleaves like lambsquarters and velvetleaf.

• Take a look at your problems weeds and also consider how much you are spending to see if you are investing in the best options

Other Thoughts…

• Diversify your management tactics!• Herbicides, cover crops, tillage vs no-till, crop

rotation, hand weeding, etc.

• START CLEAN! • The smaller the weed; the easier it is to

kill.• Kill weeds before you can see them

(residual herbicides).

2018 Pumpkin Field Day

• Thursday, September 6, 2018 - 10:00 AM• U of I Ewing Demonstration Center, Ewing, IL

• Located about 15 minutes south of Mt. Vernon; 4 miles east of I-57

• Variety Trials, Pest management trials, no-till production, and more!

• More details to come!!• Watch the IL Fruit/Veg Newsletter

Illinois Fruit & Vegetable News• Commercial Grower Newsletter

• https://ipm.illinois.edu/ifvn/• Regional updates, pest & production

information• Editors: Bronwyn Aly & Nathan Johanning• 20 issues per year

• For email notification send an email to Nathan Johanning njohann@illinois.edu

• Paper subscriptions available ($25.00/year)

Questions?

Nathan JohanningExtension Educator, Local Food Systems and Small FarmsUniversity of Illinois Extension402 Ava Rd.Murphysboro, IL 62966

njohann@illinois.edu(618)687-1727

Thank You!