Are your Marguerite daisy flowers opening bent or misshapen? Are your rose flowers crimped and crumpled on one side? Do your bean leaves have mysterious scratches on stems or leaves? One of the hardest-to-spot summer pests could be the cause. Thrips are nearly microscopic insects that thrive in warmer months and dry situations. You probably won’t see the critters themselves, although they may leave leafy plants with a silvery cast. Thrips suck plant juices, often attacking flower buds, resulting in those misshapen flowers, scarred leaves, and off-color foliage. The damage is the best evidence of their presence and simple measures can reduce their impact.
Here’s how to nip them in the bud. Monitor soil moisture closely and keep plants well hydrated. Remove infected flowers and other plant parts and dispose of carefully. Burying these deep in the compost pile should do the trick, but if you are nervous, send them out in a closed garbage bag. Encourage their natural predators-ladybird beetles (and their larvae), green lacewing larvae, and predatory mites-by planting a more diverse garden that provides food and shelter for these beneficial insects. (My list of plants is available on the Lotusland Web site, lotus land.org/bmps/beneficials.htm.)
The other bad guy this season is the whitefly. These, especially the really nasty Mexican giant whitefly, are easy to spot even though they are pretty small. These little insects are covered with a pure white powdery coating and their egg clusters, found on the underside of leaves, are also white and easily recognized. They, too, damage plants by sucking out their vital juices. Some of their favorite garden plants are canna, iris, and hibiscus. Begonias also seem to be a target. Use a strong blast of water to dislodge them and remove heavily infected foliage for careful disposal. Spread worm castings and scratch them into the top few inches of surrounding soil to help with long-term control. Their common predators are the same as those for thrips, so surround susceptible plants with others to attract ladybird beetles and green lacewings. A sharp eye and early response to both these pests will keep their damage to a minimum.
• Start seed for your giant pumpkin this month. Next month, pick one fruit to concentrate the plant’s energies, pinching out any others.
• Monitor soil moisture often and water accordingly. Inland gardens will need lots more than those still locked under the “June gloom” at the coast.
• Cover early fruiting shrubs and trees with bird netting to save the crop for your family.
• Shop for your favorite shade of Peruvian lily (Alstroemeria) this month when they are starting to bloom. A gallon-sized plant soon becomes a clump up to three feet across.
Virginia Hayes, curator of Ganna Walska Lotusland, will answer your gardening questions. Address them to Gardens, The Independent, 122 W. Figueroa St., S.B., CA 93101. Send email to firstname.lastname@example.org.