A++ for combined effort

A collaborative effort between Penn State University and the Pennsylvania Department of Agriculture is benefiting growers desiring help with pest management, especially when it comes to effective use of biological controls.

The effort – the Pennsylvania Integrated Pest Management Program (PA IPM) – provides ongoing educational programs throughout the state. IPM specialists work one on one with growers for an entire crop cycle to teach them about IPM with special emphasis on using biological control. Using these methods make the greenhouse environment safer for workers, eliminating concern for re-entry intervals, and days to harvest rules. Educators have found increased adoption of IPM techniques with the at-site, one-on-one teaching method.
 

Managing transition

Greenhouse food crop production in Pennsylvania primarily consists of the production of greenhouse tomatoes. However, other crops such as cucumbers and herbs are being produced. High tunnels are also becoming popular throughout the state, with many established greenhouse/high-h tunnel vegetable growers transitioning to an IPM program with special focus on eliminating insecticides through the use of biological controls.

Making the transition from relying exclusively on traditional pesticides to a biological control program requires more knowledge of the pest and biocontrol species, and a few shifts in management style. That is, managing pests with biological controls requires thoughtful, careful planning and the realization that every crop cycle may present a unique situation.

Growers should follow these steps:

• Start small. Learn the system in one greenhouse and expand as you gain confidence and knowledge.
• Eliminate pesticide residue. Discontinue using insecticides with residual activity at least one to two months prior to introducing biocontrols. Pesticide residues on plants and greenhouse coverings can be deadly to biocontrol agents. Consult biocontrol suppliers for information on specific chemicals that were used in the greenhouse.
• Use “soft” or “reduced risk” pesticides. These insecticidal soap, ultra-fine horticulture oil, and neem compounds should be used for treating hot spots or pests not being controlled biologically.
• Ensure sanitation through effective week management. This is critical to the success of a biocontrol program both before and during crop production. Weeds serve as reservoirs for pests and diseases and may upset the predator-prey balance you are trying to establish in the crop.
• Clean transplants. Serious pest and disease problems that plague growers throughout the growing season result from purchasing infested transplants. Selection of a reputable grower ensures a quality transplant. Inspect what you are buying. If you are growing your own transplants, follow strict sanitation procedures and inspect seedlings weekly for pest and disease development. Preventing a problem from becoming established can save a lot of time, effort and expense.
• Start early. Begin introductions of biocontrol agents, when pest populations are at low levels so that the biocontrol species is not overwhelmed. This can be determined by weekly crop inspection. For example, even though Encarsia formosa, a tiny parasitic wasp, is an excellent control for whiteflies, the wasp will not be as effective if it is released too late. This is because high populations of whiteflies produce sticky honeydew that will interfere with the parasitoid’s walking and searching speed and may even cause them to become trapped and die.
• Establish a source for purchasing biological controls. A list of distributors in the U.S. can be found at the Association of Natural Biocontrol Producers' website, www.anbp.org. Most distributors require orders to be placed by Thursday (since they must be shipped from producers of biocontrols located in Europe or Canada) for delivery the following week. Products are delivered directly to your farm or greenhouse via UPS, Airborne or FedEx. Insist on guaranteed live delivery and overnight express only.
   

Biocontrol producers screen for quality and use expiration dates. Check biocontrol shipments for this date and be cautious of distributors that do not put dates on the material. When biocontrols arrive at your operation, check for viability. Predatory mites can be monitored by shaking material onto a white sheet of paper and observing movement.

Parasitoids for aphid control such as Aphidius colemani are shipped in bottles. Within 24 hours after placement in the greenhouse check bottles for parasitoid emergence. If you observe high mortality of parasitoids call your distributor immediately. During warm weather months, biocontrols should be shipped with cooling material. It is a good practice to inform your employees that you will be receiving biocontrols so that they can be stored in a cool area if you cannot distribute them immediately.

• Develop a weekly scouting/monitoring program. Crop scouting is the cornerstone of a successful IPM program. Early detection of pests is critical in a long- term crop, such as greenhouse vegetables. Growers who scout weekly save money by applying treatments early, before a major outbreak occurs. Designate one employee who will be trained to scout for pests and diseases.
   

Scouting tools include:

• hand lens at least 10x magnification, scouting report forms, flagging tape, sticky cards (traps),
• Ph meter, soluble salts (EC) meter, and a minimum-maximum thermometer, which is useful when using biocontrols
   

When biocontrols are introduced into a crop, scouting must continue to evaluate their effectiveness. For example, when using Encarsia Formosa for greenhouse whitefly control, nymphs will turn black if parasitized. (insert picture) If using Aphidius species for aphid control, parasitized aphids appear brown or mummified. Making these observations ensure that the biocontrols you have introduced are working.
 

Conclusion

While the program discussed in this article is limited to Pennsylvania growers, growers everywhere can, and should, apply the steps outlined here for effective management of pests with biological controls. Furthermore, growers should contact their respective state departments of agriculture and university extensions to learn of similar efforts.

Ongoing education is the key to growers’ success.