At Lan Su Chinese Garden, we practice Integrated Pest Management, or IPM. IPM is an ecosystem-based strategy that focuses on the long-term prevention of pests and the damage that they cause by monitoring for pests, cultural control, manual control, biological control, habitat manipulation, and use of resistant plant varieties. Pest control methods are selected to minimize risks to human and animal health, beneficial and nontarget organisms, and the environment; harmful and toxic chemicals are used only as a very last resort.
Pests are organisms that damage or interfere with desirable plants in our fields and orchards, landscapes, or wildlands, or damage homes or other structures. Pests also include organisms that impact human or animal health. Pests may transmit disease or may be just a nuisance. A pest can be a plant (weed), vertebrate (bird, rodent, or other mammal), invertebrate (insect, tick, mite, or snail), nematode, pathogen (bacteria, virus, or fungus) that causes disease, or other unwanted organism that may harm water quality, animal life, or other parts of the ecosystem.
— University of California IPM Program
Some of the most prevalent insect pests at Lan Su are root weevils, aphids, thrips, mites, and scale insects. Biological control uses natural enemies to control pests; in the case of insect pests, there are numerous beneficial insects including nematodes, ladybugs, green lacewings, predatory wasps, and praying mantises.
Predatory mites are small, but powerhouses! They feed on all life stages of many small arthropods and especially target pest mites. Because they attack adult, juvenile, and egg stages of many pests, they are natural predators of thrips and mites. When pest populations are low, they are able to supplement their diet with pollen. This allows the predatory mites to act as “body guards” and protect plants from outbreaks even when pest populations are low.
Beneficial nematodes are microscopic soil organisms that target over 200 species of soil-dwelling insect pests, especially in their larval form (our primary target is root weevil larvae). The juvenile nematodes enter the insect and release a bacterium which rapidly multiplies, killing the host insect within 1-2 days. The nematodes and bacterium both get nutrients from the liquifying insect, and reproduce inside the cadaver for several generations. The entire life cycle of a nematode is only a few days, but in that time their population can increase by tens of thousands in a favorable environment.
Once the weather is consistently above 60 degrees Fahrenheit at night, we also deploy green lacewing eggs, minute pirate bug, and purple scale predator to help mitigate the rise in pest issues that coincides with new leafy growth.
If you would like more information about Lan Su’s IPM program, please contact Lan Su’s Curator of Horticulture, Josie Losh, at [email protected].
