Page 16 - 2015 Spring Gazette
P. 16
STOPPING
the Able Aphid
Image: Black aphids on sedum Image: Oleander aphid with Image: Small aphid colony Image: Sooty mold
prominent cornicles on calibrachoa
By Tami Van Gaal, GGSPro Technical Support Specialist
Aphids present the perfect storm as a greenhouse Frequent and regular scouting is important because populations
pest. They bring to the table a very high build quickly. Sometimes signs are quite visible: the aphids are seen,
reproductive rate, a preference for popular spring distortion exists or white, cast skins accumulate. Aphids repeatedly
crops, negative and visible impacts on plant shed their exoskeletons; the cast skins can be seen clinging to
health, low customer tolerance and emerging leaves near or below the colony, decreasing salability. Aphids also
pesticide resistance. An added predicament: excrete great amounts of shiny, sticky honeydew. Honeydew then
Some growers face pressure to avoid use of an supports growth of an unsightly, but non-pathogenic, black fungus
effective tool, the neonicotinoids. In the midst called sooty mold. Beat tests will reveal aphid colonies hidden
these barriers and obstacles, what is a grower in foliage. Hold white paper under the plant and gently shake
to do? GGSPro has a few ideas to help gain the or tap the foliage to dislodge pests and cast skins. Sticky cards
upper hand on this prolific little beast. will capture the winged aphids, whose presence should always
send you searching for the exploding colony. Scout historic hot
Let’s start with a quick review of aphid biology. Aphids feed by sucking spots and preferred aphid crops carefully for early problems (e.g.,
plant juices from soft tissues. They like growing tips, but can be found petunia, calibrachoa, gerbera, pepper). Also train staff to isolate
along stems or covering lower leaf surfaces. Aphids can even attack and inspect incoming material and encourage sharp eyes on the
plant roots. Reproduction is generally asexual. This means the offspring transplant line.
share nearly identical genes, allowing resistance to develop quickly. An
aphid that escapes treatment will pass those advantageous/resistant GGSPro promotes an integrated approach to pest control. This
gene(s) to ALL her offspring. Aphids pack another reproductive punch: starts with culture. Aphids can be discouraged by avoiding soft,
They give birth to live young carrying developing nymphs. It’s no wonder lush growth, so be sure to avoid luxury nitrogen levels. When
that the population can seem to explode overnight. released early and properly, biological control agents (BCAs) can
be effective. Parasitic wasps (Aphidius spp.), predatory midges
Aphid size and color vary across and within species, with several (Aphidoletes aphidimyza) and lacewing larvae (Chrysoperla
different species common in greenhouses, including green peach, carnea) work well in managing aphids. Aphidius species selection
cotton/melon, foxglove and potato aphids. However, aphids as a group is based on aphid species and season, and other release details
are relatively easy to identify by the unique cornicles at the rear of their favor success in BCA use. Contact GGSPro to learn more.
bodies. Aphid nymphs are simply small versions of the adults, and most
aphids are wingless. Winged forms develop when dispersal is needed Several factors impact chemistry choices for aphid control. Options
to support an expanding aphid colony’s need for food. If you see winged are restricted for edibles, making BCAs especially helpful. Some
aphids, the outbreak is ahead of your pest control measures and/or your drench products offering longevity in the plant, such as Flagship,
scouting has failed. Marathon and Safari, remain strong and effective options for
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