Solid pest management starts with propagation

When it comes to pest management, the best place to start your program is from the beginning, so start with propagation. If your starter plants are not clean, it’s going to be an uphill battle.

If you grow your own stock plants, keep them clean. This can be challenging because these plants are often allowed to grow large and dense to produce many cuttings. Getting good spray coverage on plants with dense growth can be difficult. Often pest populations seem to be under control, but their numbers are frequently just knocked back. In these situations, systemic insecticides can be useful, but remember they may not control all pests present. Make sure your target pest is on the product label after making a positive identification.

Cuttings inspections
Once cuttings have been taken (or when you buy them in), conduct a thorough inspection to check for potential problems. You may see large adult insects, but the tiny eggs and immature insect stages can easily slip by. When cuttings are shipped in, they often arrive in large volumes, and frequently it’s a race against the clock to stick them. This rush may not leave time for adequate inspections.

Try pre-treating the new cuttings before sticking them. Researchers in Canada have been looking at immersing cuttings in treatments of hot water, Safer Insecticidal Soap (potassium salts of fatty acids 2.0 percent) or Landscape Horticultural Oil (mineral oil 99 percent). The chance of developing resistance to these products is slim, which helps preserve the viability of other chemical controls.

Stop pest problems at the start of the production cycle,
and plants will be cleaner through finish. Photo: Suzanne Wainwright-Evans.Canadian researchers studied chrysanthemums and poinsettias. They found hot water can be an effective way to help control western flower thrips (WFT). Hot water demonstrated a high mortality (more than 80 percent) of second-instar larvae and adult WFT. These results were obtained at 102°F for 30 minutes or 104°F for 15 minutes. Insecticidal soap treatments at 40 ml/L provided low mortality of adult WFT, less than 75 percent. But the most effective control was the horticultural oil treatments, resulting in 100 percent mortality of WFT adults and 64-82 percent mortality of both the first and second-instar larvae.

Pre-emptive strikes
Clean cuttings do not ensure that pests will not arrive on their own. One of the easiest things to do is use sticky cards. The yellow cards will attract most flying insects including fungus gnats, shore flies, thrips, winged aphids, whiteflies and others. Blue cards work well for thrips. But sticky cards will not help you monitor for mites, because mites do not fly.

Opit, G. P., G.K. Fitch, D.C. Margolies, J. R. Nechols, and K. A. Williams. 2006. Overhead and Drip-tube Irrigation Affect Twospotted Spider Mites and their Biological Control by a Predatory Mite on Impatiens. HortScience. 41(3):691-694

W. Romero, c. Scott-Dupree, G. Murphy, T. Blom and R. Harris. 2010. Reduce Risk Control Methods for Insect Pests on Cuttings.  Poster.