The avocado (Persea americanus) decorates salads and binds guacamole, and the creamy green fruit provides plenty of nutrition. If you are fortunate enough to live in U.S. Department of Agriculture plant hardiness zones 10 through 12 -- avocados grown indoors seldom bloom -- you can grow your own trees. A few tricks will help keep the few bugs that bother them away.
Avocado trees are evergreen trees native to Central America that thrive in well-draining, neutral to slightly alkaline soil. They grow to 30 feet or more in their native range and prefer soil that stays moist near the surface. Cold resistant varieties, including “Haas” and “Susan” allow trees to grow throughout USDA zone 10 where occasional storms or frosts might cause more tender hybrids to drop their leaves. Several minor pests can be easily discouraged from eating your avocado's leaves.
Good After Bad
Several types of mite, including the avocado brown mite and six-spotted mite, establish colonies on the undersides of avocado leaves, spinning webs -- mites are arachnids, not insects -- raising their young, and feeding along veins. A few mites won’t do much damage, but a large colony can destroy foliage, lessening its photosynthesis efficiency. Beneficial mites, such as western predatory mite, help discourage pests. Because mites favor hot, dusty conditions, plant your tree away from roadways or open fields to minimize exposure to dust during the heat of summer. Although avocados need sun, planting among other trees, and near lawns helps keep the air around avocados cooler in summer. Regular watering lessens heat stress, another mite attractant.
Leafrollers, including the orange tortrix, and light brown apple moth favor tender new avocado leaves. Eggs laid by fruittree leafroller moths produce larvae in the form of caterpillars, which form webs on the leaves or eat in patterns that force leaves to roll up. The larvae feed from March to mid-May and then pupate and emerge as moths from May through June. Plant avocados well away from oaks (Quercus spp.), which generally grow in USDA zones 4 through 9, but may grow in the same zones as avocados, which might also attract fruittree leafrollers. A resident colony of tachinid flies or ichneumonid wasps might head off leafroller population growth.
Thrips and Whiteflies
Greenhouse thrips and ash whiteflies are tiny sucking insects that might gather on the undersides of avocado leaves to feed. Not all thrips are nasty -- black hunter and sixspotted thrips feed on mites. Avoid high-nitrogen fertilizers, which encourage fast growth, attracting these pests. Avoid planting your avocado near a perennial bed or vegetable garden, where thrips and whiteflies love to feed and plant your tree where air circulates freely to discourage landings. Reflective mulch confuses thrips and whiteflies by directing UV light where they don’t expect it.
- Missouri Botanical Garden: Persea Americana
- Hass Avocado Board: Avocado Nutrition Facts and Label
- Purdue University Horticulture: Avocado
- University of California Integrated Pest Management: Avocados
- University of California Riverside Applied Biological Control Research: Trioza (Hemiptera: Psylloidea: Triozidae)
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