Trap crops, indicator plants and banker plants:

Tools for IPM in Greenhouse Production

Trap crops, indicator plants and banker plants:

Tools for IPM in Greenhouse Production

Elizabeth LambNew York State IPM ProgramCoordinator for Ornamentalseml38@cornell.eduwww.nysipm.cornell.edu

Elizabeth LambNew York State IPM ProgramCoordinator for Ornamentalseml38@cornell.eduwww.nysipm.cornell.edu

All photos by E. Lamb except where otherwise noted

Indicator plants, trap crops and banker plants provide additional

tools for managing pests in greenhouses

Indicator plants, trap crops and banker plants provide additional

tools for managing pests in greenhouses

Indicator plantsIndicator plants• Indicator plants are usually species or

varieties that are particularly susceptible to, or tolerant of, certain conditions– Environment

• Ground ivy in shady lawns• Salt tolerant species• Phenology for insect development

– Gypsy moth egg hatch corresponds to the first bloom of Eastern dogwood in Ohio

• Disease and insect presence– Indicators are more attractive to insects than

crop

• Indicator plants are usually species or varieties that are particularly susceptible to, or tolerant of, certain conditions– Environment

• Ground ivy in shady lawns• Salt tolerant species• Phenology for insect development

– Gypsy moth egg hatch corresponds to the first bloom of Eastern dogwood in Ohio

• Disease and insect presence– Indicators are more attractive to insects than

crop

Potato chunks as indicator for fungus gnat larvae

Virus Indicator PlantsVirus Indicator Plants

• Diseases indicated– Impatiens Necrotic Spot Virus (INSV)– Tomato Spotted Wilt Virus (TSWV)

• Vectored by– Western flower thrips

• Petunia– cultivars Summer Madness, Super Blue

Magic, Calypso, Red Cloud

• Fava beans– cultivar Aquadulce

• Diseases indicated– Impatiens Necrotic Spot Virus (INSV)– Tomato Spotted Wilt Virus (TSWV)

• Vectored by– Western flower thrips

• Petunia– cultivars Summer Madness, Super Blue

Magic, Calypso, Red Cloud

• Fava beans– cultivar Aquadulce

Virus Indicator PlantsVirus Indicator Plants

• Characteristics– Very attractive to western flower thrips– Feeding scars show up quickly and

infected lesions form quickly (2-3 days)– Petunias do not serve as a source of

virus• Not true of fava beans but seed may be less

expensive– Therefore must remove infected fava beans as

soon as possible

• Remove infected petunia leaves but plants can stay

• Characteristics– Very attractive to western flower thrips– Feeding scars show up quickly and

infected lesions form quickly (2-3 days)– Petunias do not serve as a source of

virus• Not true of fava beans but seed may be less

expensive– Therefore must remove infected fava beans as

soon as possible

• Remove infected petunia leaves but plants can stay

Photos: Tina Smith, UMass Extension

Blue attracts the thrips but the plates aren’t sticky so the thrips feed on the indicator plants rather than getting stuck.

Tomatoes as indicator plants for whitefly in poinsettia

Tomato plant

Photo: Graeme Murphy

Trap cropsTrap crops

• Trap crops are most often used for insect pest control– Perimeter trap cropping in field vegetables– Trap crops interspersed in greenhouse

ornamentals

• Characteristics– Species or cultivar used needs to be more

attractive to pest than crop is

• Trap crops are most often used for insect pest control– Perimeter trap cropping in field vegetables– Trap crops interspersed in greenhouse

ornamentals

• Characteristics– Species or cultivar used needs to be more

attractive to pest than crop is

Perimeter trap cropping of collards for cabbage - diamondback moth

Other vegetable trap crop systems:Hubbard squash for other Cucurbita - cucumber beetles Cherry peppers for bell peppers - pepper maggots

Photo: T.J. Boucher, University of Connecticut

• Methodology– Trap crop must encircle other crop– Control pest on trap crop as soon as it is

seen

• Advantages– Lower use of pesticide– Maintains populations of indigenous natural

enemies

• Attractiveness as a problem?– Will the trap crop plants attract more

insects than would have been there anyway?

• Methodology– Trap crop must encircle other crop– Control pest on trap crop as soon as it is

seen

• Advantages– Lower use of pesticide– Maintains populations of indigenous natural

enemies

• Attractiveness as a problem?– Will the trap crop plants attract more

insects than would have been there anyway?

While perimeter trap cropping can be used in the greenhouse, it is more common to see the trap crop interspersed among the crop plants

Some examplesSome examples

• Whitefly in poinsettia– Tomato– Eggplant

• Thrips in chrysanthemum– Gerbera – Verbena– Chrysanthemum - more susceptible

cultivar

• Whitefly in poinsettia– Tomato– Eggplant

• Thrips in chrysanthemum– Gerbera – Verbena– Chrysanthemum - more susceptible

cultivar

For attracting western flower thrips, the trap crop is in flower before the saleable crop

At all 3 distances from the release point, the chrysanthemum plants with open flowers were more attractive to the thrips than plants with foliage, buds or buds showing color (crack buds).

Table from Buitenhuis, Shipp, Jandricic and Short, Greenhouse Canada, September 2006, pp 10, 12

What factors do you need to consider when using trap

crops?

What factors do you need to consider when using trap

crops?• Placement

– Near vents for pests moving in from outside– Throughout crop

• Number– How far does pest move?

• Stage of crop plant– Flowering vs. vegetative

• Control on trap crop or not– Chrysanthemum example - systemic control

on trap plants

• Placement– Near vents for pests moving in from outside– Throughout crop

• Number– How far does pest move?

• Stage of crop plant– Flowering vs. vegetative

• Control on trap crop or not– Chrysanthemum example - systemic control

on trap plants

Eggplant in gerbera crop

Banker plantsBanker plants• Banker plants serve as a site for rearing

biocontrol agents in the greenhouse by providing them with an alternative food source.

• The banker plants can consist of the same crop/crop pest as that you are trying to control, or can be an alternate host and prey– Bird cherry aphid on wheat for green peach aphid

control– Greenhouse whitefly on eggplant for greenhouse

whitefly control

• Banker plants serve as a site for rearing biocontrol agents in the greenhouse by providing them with an alternative food source.

• The banker plants can consist of the same crop/crop pest as that you are trying to control, or can be an alternate host and prey– Bird cherry aphid on wheat for green peach aphid

control– Greenhouse whitefly on eggplant for greenhouse

whitefly control

Banker plants for aphid control

Banker plants for aphid control

• Bird cherry aphid does not infest plants other than grasses but the parasitoid (Aphidius, commonly) can easily more throughout the greenhouse to parasitize other aphids

• Need a continuous supply of infested wheat (or barley or oat) plants to provide an alternate host when aphid numbers in crop decrease

• This system is being sold as a unit by biocontrol companies or can be a do-it-yourself operation

• Bird cherry aphid does not infest plants other than grasses but the parasitoid (Aphidius, commonly) can easily more throughout the greenhouse to parasitize other aphids

• Need a continuous supply of infested wheat (or barley or oat) plants to provide an alternate host when aphid numbers in crop decrease

• This system is being sold as a unit by biocontrol companies or can be a do-it-yourself operation

Parasitized aphids on wheat banker plants

Grower with new pots of wheat in greenhouse and with aphid infested wheat in cooler before placing pots in greenhouse

Banker plants dispersed in greenhouse

Note irrigation - this system saves bench space for crop and allows best maintenance of banker plant

Old plants are left in the greenhouse for parasitoid to emerge from parasitized aphids

Eggplant trap crop/banker plant for whitefly on

poinsettia

Eggplant trap crop/banker plant for whitefly on

poinsettia• New system not yet commercially

available• Eggplant is more attractive to white fly

than poinsettia– Eggplant acts as an indicator plant, a trap

crop and a ‘nursery’ for biological control agents

– Pest populations on eggplant are inoculated with parasitoids to provide beneficials for crop

• New system not yet commercially available

• Eggplant is more attractive to white fly than poinsettia– Eggplant acts as an indicator plant, a trap

crop and a ‘nursery’ for biological control agents

– Pest populations on eggplant are inoculated with parasitoids to provide beneficials for crop

Note whiteflies on undersides of leaves

Eggplants inoculated with Encarsia formosa for control of greenhouse whitefly and Eretmocerus mundus for control of Bemisia whitefly

Eggplants interspersed in poinsettia crop

Table from Osborne and Barrett, 2005, You Can Bank On It, Ornamental Outlook, September, pp 26-27

While this system is used less commonly, there are indications that it can aid in the control of whitefly in poinsettia

Supporting informationSupporting information• Lance Osborne, University of Florida

– http://mrec.ifas.ufl.edu/lso/banker/banker.htm• You Can Bank on It, Ornamental Outlook, September

2005, pp 26-27

• Graeme Murphy, OMAFRA– http://www.omafra.gov.on.ca/english/crops/hort/

news/grower/2004/07gn04a1.htm• Trap Crops and Banker Plants - thinking outside the pest

management tool box

• Leanne Pundt, University of Connecticut– http://www.hort.uconn.edu/ipm/greenhs/htms/

tospov.htm• Using Indicator Plants to Detect Tospoviruses

• Lance Osborne, University of Florida– http://mrec.ifas.ufl.edu/lso/banker/banker.htm

• You Can Bank on It, Ornamental Outlook, September 2005, pp 26-27

• Graeme Murphy, OMAFRA– http://www.omafra.gov.on.ca/english/crops/hort/

news/grower/2004/07gn04a1.htm• Trap Crops and Banker Plants - thinking outside the pest

management tool box

• Leanne Pundt, University of Connecticut– http://www.hort.uconn.edu/ipm/greenhs/htms/

tospov.htm• Using Indicator Plants to Detect Tospoviruses