Scouting and Monitoring for Pests

Weekly monitoring for pests and disease is critical for any diligent grower and crucial for implementation of a a successful biocontrol program. It is also the basis for IPM decision making. Consistency is the key to this process. Consistency in who is scouting, in timely scouting and consistency in observation techniques and reporting.

Biological controls are most effective when applied preventatively, therefore tracking pests and finding them early will allow treatments to be applied before heavy pest populations occur, saving time and money. Having the right tools will make the process effective and efficient.

Scouting Tools

clip on microscope

Hand lens 10x
Proscope for Smartphone or tablet
Notebook for recording observations
Flagging tape or colored flags
Sticky cards with stakes/clips
Permanent marker for sticky cards
Plastic bags for plant samples
Ph and EC meter to check cultural conditions
Trained personnel

Developing a Scouting Program

Maintain a notebook and record data weekly from both sticky cards and plant inspections.
Scout weekly, preferably on the same day each week.
Look for trends across seasons and crops.
Keep all spray records and biocontrol application records available. These will give you a complete picture of the program. For instance, how are the pest populations after the last spray or beneficial insect application?
Scout clean areas first and move to heavily infested areas last.
Scout a minimum of 10 locations per 1,000 sq. ft. (For eriophytid mites, increase to 50 locations/1,000 sq. ft.).
Use sticky cards at a minimum of 1 card/ 1,000 sq. ft.
Replace sticky cards weekly or reuse if pest counts are low.
Place sticky cards vertically just above the crop canopy, near greenhouse vents and doors and along the periphery.
Track all biocontrol applications: Which predators did you apply? Where? How many?

Yellow sticky cards are used to detect the presence of flying pests, such as thrips, fungus gnats, shore flies, winged aphids and white fly. Blue sticky cards attract thrips. Making a habit of taking weekly counts and changing sticky cards will help you detect new pests, increases in the pest populations and efficacy of treatments. With time you will develop thresholds for action. For instance, a threshold may be when you see 10 fungus gnats on a weekly sticky card it's then time to treat with nematodes.

It can be helpful to enter your weekly counts into an excel spreadsheet and create graphics to visually show the rise and fall of pest populations and look at seasonality. Once you accumulate enough of this data you can then treat preventatively. See example below.

If you are using beneficial insects, become familiar with both the pests and the predators and their life stages. For instance, two spotted spider mite eggs are round while predator mite eggs are pear-shaped. Look for signs, which are the actual presence of a pest. This could be webbing from a spider mite or aphid mummies from Aphidius the parasitic wasp.

Plant Inspection Counts

Start early, even before the crops arrive in the greenhouse. The importance of consistency from week to week should not be underestimated. Inspect 10 locations/1,000 sq. ft. Develop a sampling system that works for you. For instance, will you take a certain number of leaves per row? Per room? Per variety? Will you collect the leaves in sampling bags and count pests and predators in a different room? Or will you simply inspect the leaves, top and bottom, of the plant and record the data in the greenhouse? Will you actually count the pests or will you develop a rating system like 1-5 which signifies a range from no pests to heavy pest pressure.

Education and Training for Staff

Having a designated scout is important, but educating all employees working in the greenhouse is equally important. They can assist with detecting new issues and know the difference between living and dead aphids on a plant. Additionally, accurately communicating pest issues with a biocontrol supplier can help everyone achieve best management and apply at appropriate rates. Pictures are a great tool for identifying pests, sharing information and communicating potential problems. Using a pro scope or clip on microscope can be a helpful monitoring tool for documentation, communication and proper identification. Please see the resources below for more information on scouting and monitoring.