Integrated Pest management in the greenhouse

Insects & Diseases

IPM Defined: 

"IPM is a sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health, and environmental risks."

IPM Pest management, not eradication, is the goal.  Manage pests below the economic threshold. 

Economic Threshold How would you define it?  The point at which the disease or pest infestation begins to diminish the quality of the crop. 

Economic Thresholds 

Thresholds should be quantitative and grower driven.  For example, thresholds could be based on

the average number of pests per trap each week.  the percent of plants or leaves found to be damaged or infested during visual inspection.  the number of pests dislodged per shake sample.

Economic Threshold 80

Avoid exceeding economic injury level

70

EIL

60 Apply controls

50

ET

40

Average density

30 20 10

0

Time

Economic Thresholds Vary depending upon the crop.  Bacterial Leaf Spot on Poinsettia: 

 Devastating!



Bacterial Leaf Spot on Greenhouse Tomatoes:  Not such a big deal. Why?



Insects & diseases on ornamental crops grown in nurseries:  Big deal? Yes or no?

Scouting and Record Keeping

Also called “monitoring’.  Perform weekly.  In greenhouses focus monitoring near doorways, vents and fans.  1 card per 1,000 square feet. 

 Yellow: attracts most flying insects  Blue: for thrips



Replace cards on a regular basis.

Cultural IPM Tactics

Sanitation 

The goal of sanitation is to eliminate all possible sources of the pest.  weed removal inside and outside the

greenhouse. ○ grass flowering-increase in thrips population

 weed removal around nurseries.  dispose of dead/diseased plants.  In greenhouses: ○ quarantine infested plants in a separate room. ○ medium pasteurization (especially if it contains soil). ○ algae control-fungus gnats.

Watering 

Too much moisture:  leaf diseases  root rots  fungus gnats  algae



Too little moisture:  stresses the plants and predisposes it to

disease  hot, dry conditions favor spider mites

Temperature Plants begin to stress at temperatures of 95 degrees F. and higher.  Temperature fluctuations. 

Growing Medium Should have good aeration/drainage.  Monitor EC. 

Variety Selection Choose insect/disease resistant varieties.  If possible, rotate crops. 

Physical/Mechanical IPM Tactics

Insect Screening

Biological IPM Tactics 

The use of living organisms to control pests.

Lady Bugs

Parasitic Wasps

Predatory Mites

Chemical IPM Tactics: Biorational Pesticides  Conventional Pesticides 

Biorational Pesticides: Insecticidal Soaps  Horticultural Oils  Bacillus thuringiensis-bacteria  Beauveria bassiana-fungus that infects the chitin exoskeleton of many pests  Diatomaceous Earth  IGR’s 

 kill insects by disrupting their development

Conventional Pesticides Licensed Applicator  WPS  Re-entry Times  Residue  Resistance 

 rotate between groups/active ingredients

Major Insect Pests of Greenhouse-Grown Bedding Plants:

Aphids  Thrips  Fungus Gnats  Whiteflies  Shore Flies  Leafminers  Mealybugs  Spider Mites 

Aphids

Immature & Adult Greenhouse Thrips

Thrips Life-Cycle

Greenhouse Whiteflies

Mealybug excreting honeydew

Two-spotted Spider Mite

Red Spider Mite

END