Mstr Grdnrs photo

Look Carefully. This apple leaf is looking thrippy. Thrips feed on the inner cells of the leaf distorting the surface. Small brown spot appear on the underside as leaf tissue dies.

An ounce of prevention is worth... what was it my grandmother used to say? a pound of cure? Integrated pest management is an integral component of the education that Master Gardeners receive in their 15 weeks of intern classes. The classic integrated pest management (IPM) model begins with a hierarchy of management options, a pyramid with “prevention” at the base, often in green, then “cultural,” “mechanical,” and “biological” in the ascending blocks gradually turning to yellow. “Chemical” is billed in red, at the top: the last resort.

Prevention begins with “right tree, right place.” By selecting landscape plants that are healthy and biome appropriate, you will head off long-term problems relating to soil and climate maladaptation that can be difficult or impossible to remediate.

Cultural methods to prevent pests and diseases include proper planting, adequate irrigation, and plenty of organic mulch to slow evaporation and regulate soil temperature. Protect trees from mechanical injury (vehicles, weed eaters). Protect the root zone from compaction and other injury. Good sanitation and weed control are as valuable in your back yard as they are to commercial growers.

Mechanical controls are the next step to take when cultural controls are inadequate. Pruning out infested or infected branches, hand-picking small infestations, or using a stream of water to dislodge crawling insects can be effective. Other mechanical controls include barriers to reduce access and removal of weeds that host some part of the life cycle of a known pest.

Biological controls can be imported predators for exotic pests, but we have a wealth of natural predators and parasitoids that make a living largely unnoticed. Some of these animals are showy, like lady beetles, or large, like praying mantis, but most are small and go about their business unseen to the casual observer. The beneficial effects of many insects are accomplished by the carnivorous larvae of an adult that feeds only on pollen, or nectar, or not at all. And for these animals, we are cautious about chemical controls. (For more information, see Circular 607 from New Mexico State University at aces.nmsu.edu/pubs/_circulars/CR607.)

Chemical controls, albeit an essential tool in IPM, are the last resort, to be used with utmost care. Chemicals have various modes of action (the way in which they disrupt, disorient, or kill) and if used repeatedly can induce resistance — for example, the Anopheles mosquito that transmits malaria is developing resistance to pyrethroids. Used indiscriminately, chemicals can wipe out beneficial insects and damage the environment in unexpected ways.

The goal of IPM is controlling pests and pathogens at acceptable levels while minimizing harmful effects on the environment. For commercial growers “acceptable” typically means economically acceptable: balancing costs against yield. In public spaces and for nonprofit organizations such as the Xerces Society, the importance of minimizing environmental risks and maximizing biodiversity has become paramount. For the homeowner, acceptable levels of a pest or pathogen will require some thought. The process that defines IPM integrates the hierarchy of management options into a dynamic, iterative process that begins with knowledge: knowledge of the plant, its requirements, its common pests and diseases, and knowledge of the pests and diseases’ life cycles, alternate hosts, and natural enemies. Prevention strategies may not be 100 percent effective, so monitoring is crucial. Use pheromone and sticky traps as well as the ever-popular low-tech strategy of turning over a leaf to see what’s laying eggs or reproducing. Visual inspection can hardly be emphasized enough.

When monitoring reveals disease or pest densities that are unacceptable, decide on an intervention plan. After implementing management options, evaluate the results. This process should be iterative, resulting in expanding knowledge. If your plan includes the use of chemicals, be sure to understand the life cycle of the insect involved; most are effective in only one phase of the animal’s life cycle. You can check for side effects that may not be on the product label at www2.ipm.ucanr.edu/beeprecaution.

Just before sitting down to write, I contacted our city IPM program manager, Victor Lucero. Monitoring is a major component of his professional duties. What he was seeing as of May 11 were eggs of piñon needle scale beginning to hatch, the peak of the Nantucket pine tip moth overwintering generation (May 4), western tent caterpillars making “tents” in various broadleaf trees and shrubs, flea beetles migrating from stands of weeds into gardens, and the flight of the cutworm moths (family Noctuidae). Nearly everyone noticed the moths — they prompted a piece in a recent issue of The New Mexican. Lucero’s report ended with an upbeat observation: Santa Fe’s ash trees are sporting new foliage after an April frost thwarted the first flush of new leaves.

What to do with this information? Look carefully at your landscape plants. If you have tiny black “beans” on your piñon needles, visit the Extension Office Hotline webpage on the Santa Fe Extension Master Gardener’s website. Codling moth in your apple tree? See CSU’s guide to controlling codling moth. Gossamer tents appearing in shrubs or trees? CSU’s website also has info on them. For more detail on IPM practices, check out “IPM for Home Gardeners” on NMSU’s website. There is a wealth of research-based guidance published by the extension services of land-grant universities around the country.

If you need help with diagnosis or pest identification, visit the Extension Master Gardeners website (sfemg.org) and click on the “Gardening Questions?” link. And if a tree service has offered an expensive solution to a problem tree, contact your county extension agent, Tom Dominguez, at 505-471-4711, for a second opinion.

Pam Wolfe holds a master’s degree in applied mathematics and worked as a biostatistcal consultant to researchers at the Anschutz Medical Campus in Aurora, Colorado, until her retirement in 2012. She is a graduate of the Denver Botanic Gardens Botanical Illustration program, an Extension Master Gardener, and a Santa Fe Native Plants Project (SNaPP) team member.

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