Large-scale Net House for Vegetable Production: Pest Management

Successes & Challenges

Ayanava MajumdarExtension Entomologist (Peanuts, Vegetables)

State SARE Coordinator (Auburn U)Alabama Cooperative Extension System

&Mike Powell

American Farm Systems (PolyProductos de Guatemala)

Vegetable Production in Alabama

• 50 vegetables produced• 2006: 5700 acres >> 2008: 5,950 acres• 100% fresh market produce• Value: ~$17 million• Tomato: ~1300 acres = $12 million• 6 organic producers

Need for net house research• Insect pest pressures in southeast U.S. are very

high (struggle for organic producers)• Vegetable production is insecticide dependent• Blocking insects by physical exclusion reduces

insecticide use (nothing new!)• Net house is a closed crop production system that

excludes insect pests via a physical barrier.• Could be of interest to organic farmers…

Past research on insect netting• Martin et al. (2006): Africa, cabbage

production, 25-mesh, reduction in caterpillars - Spodoptera littoralis 66%, Trichoplusia ni 97%, Hellula undalis 88%, Plutella xylostella (moths) 78%, no change in aphids (6% infestation), net return $247, 3-10x spray reduction

• Fang-Cheng et al. (2010): China, tomato seedlings, 50-mesh, whitefly reduction 98%, 5x spray reduction, small structure

• Harmanto (2006), Mutwiwa & Tantau (2009): Germany, greenhouse + netting (50-mesh), 40% reduction in air velocity, thrips & whitefly reduction on tomatoes

Low net house (Malaysia)

Movable net house (Africa)

Past research on large net houses• Talekar et al. (2003): Taiwan, 15

crop cycles of leafy greens, 2 m or 6.5 ft structure, 32-mesh net

• Kaur et al. (2004): India, egg plant production, doubled plant yield in net house, mesh size??

• Anonymous (2010): Malaysia, okra & tomato

• Anonymous (2008): Vietnam, cost $186

• Guatemala, Israel: commercial tomato & bell pepper in net houses

Large net house (India)

Large net house (Vietnam)

Large net house vegetable production (Guatemala)

Photos:Polyproductos de GuatemalaTop Greenhouses Ltd., Israel

Large commercial scale net house

Commercial net houses in the U.S.Top Greenhouse Ltd., Israel: flat net houses on 280,000 m2 (~70 acres) in CA; bell pepper, tomato, chili production.

Commercial citrus production, FL

50-mesh fabric (any between above 16- to 50-mesh is fine)Mesh size depends on target insect & costHeight provides air movement…fans can also be installedCrops, 2010: Celebrity tomatoes, California Wonder peppers

Location: Baldwin County, AL Dimensions: 150 ft x 46 ftEntrance: Double door

First net house in Alabama (2010)

The making of a net house… April 2010: Setting up the poles April 2010: Sewing the long net pieces

17-ft

14-ft

April 2010: Stretching the support cables

May 2010: Fabric on cable with S-hooks

Soil preparation before sealing side-walls

17 ft

14 ft

10 ft

Mid-May, 2010

40% black shade cloth for cooling the interior!

Crops grown with partial success (Year 1)

Bell peppers Tomatoes

Temperature and humidity challenge*MICROCLIMATE INSIDE

NETHOUSE CLIMATE OUTSIDE (AWIS)

MonthTemperature

(F)

Range of Relative

Humidity (%)

Average Temperature

(F)

Average Relative

Humidity (%)Rainfall (inches)

Early May NA NA 77 93 2.04Late May 69-125 28-99 84 100 5.13Early June 68-122 26-99 82 94 2.4Late June 75-114 35-99 84 98 1.9Early July 76-102 59-98 84 98 0.5Late July 76-113 42-99 113 100 1.37Early August 77-138 39-99 85 98 2.31Late August 75-139 38-95 88 100 6.28Early Sept. NA NA 81 96 3.43Late Sept. NA NA 78 95 3.95

*Year 2010 was an unusually dry and hot year in Alabama: increased disease pressure and shocked the plants

AWIS = Alabama Weather Information System

Does net house block insect pests?

Month Tomato fruitworm

Tobacco budworm

Loopers Beet armyworm

Fall armyworm

Net house

Open field

Net house

Open field

Net house

Open field

Net house

Open field

Net house

Open field

May 0 1 0 2 0 0 0 8 0 13June 0 1 0 2 0 17 0 23 0 15July 0 2 1 23 0 27 0 40 2 11August 0 7 0 10 0 23 0 69 4 11Sept. 0 8 0 5 0 37 0 75 5 14Mean(± SD)

0 3.8 (± 3.4)

0.2 (± 0.4)

8.4(± 8.8)

0 20.8(± 13.7)

0 43 (± 28.9)

2.2 (± 2.3)

12.8(± 1.8)

% reduction

100% 98% 100% 100% 82%

ANOVA F = 6.171, P = 0.038*

F = 4.338, P = 0.071

F = 11.494, P = 0.009**

F = 11.092 P = 0.01*

F = 66.881 P = 0.0001*

Pheromone trap catches (moths)

Trapping method: Sticky wing trap with replaceable bottom were used for season long monitoring of moths. Traps were serviced every 10 days.

Does net house block insect pests?

Armyworms HornwormNet house Untreated

Control (outside)

Net house Untreated Control

(outside)Insect numbers (40 plants) 7 32 0 17% reduction 78% 100%ANOVA F = 16.845,

P = 0.0001**F = 15.852,

P = 0.0001**

Caterpillar counts: Net house vs. conventional vegetables

Sampling method: Number of caterpillars in 10 plants every 10 ft of row. Plants sampled from 4 locations each row (4 replications). Sampling done in July 2010.

Insects in a net house• Cotton aphid (Aphis gossypii) and potato aphid

(Macrosiphum euphorbiae) outbreaks in July.

• Managed with one spray of Fulfill 50WDG (selective feeding blocker)

• Armyworm moths lay eggs on fabric near joints

• Grasshopper infestation may start from ground

• Ants in the doorway

Ants in doorway

Armyworm eggs on fabric

Grasshopper resting on sidewall

Future research on net house

Heat stress and diseases like Pythium root rot on tomatoes

Exclusion of natural enemies & pollinators: may need inundative release of parasitoids and bees??

Net house for season extension: raising seedlings within the structure vs. outside transplants?

Use of microbial formulations?

Summary of net house research• Heat stress and humidity cause insect and disease flare-ups• Moths significantly blocked by net house (80 to 100%) • Net house significantly reduced caterpillars (except armyworms)

• Vegetables outside net house sprayed twice each week• One insecticide application for aphids in net house• Yield data not collected in 2010 • Findings are in accordance with reports by • Martin et al. (2006): major reduction in insecticide sprays• Talekar et al. (2003): armyworms and grasshopper

outbreaks

QUESTIONS?