Two-spotted Spider Mites have been observed on mums. They feed primarily on the undersides of leaves removing plant sap with their stylet-like mouthparts. The feeding damage causes the leaves to have a “stippled” appearance that appears on the upper sides of the leaves. Look on the underside of the leaves for the mites and their eggs.
Insects and Mites
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2017-2018 New England Greenhouse Floriculture Guide
300+ pages of current recommendations for nonchemical and chemical management of greenhouse insects, mites, diseases, weeds and algae, plus recommendations for using plant growth regulators.
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Some growers shut down their greenhouses for a few weeks during the winter expecting the cold temperatures to be sufficient to freeze and eradicate all of their pest populations. However, some pests can survive and continue on your spring crops, especially if infested debris is left in the greenhouse.
Sweetpotato whiteflies Bemisa tabaci have been observed on poinsettias since early in the growing season. While many growers are using biological controls and are keeping them in check there may be situations where late season treatments may be necessary.
Begonia plants (April) in greenhouse, thought to have been eaten by voles.
The tarnished plant bug is a very general feeder, attacking many kinds of trees and herbaceous plants. It feeds on many flowers including dahlia, aster, calendula, chrysanthemum, cosmos, gladiolus, poppy, salvia, daisy, sunflower, verbena, zinnia, and others. It has piercing-sucking mouth parts as do all the true bugs. The long sucking mouthpart is inserted into the plant tissues and introduces toxic saliva into the plant as it feeds.
A MA grower has reported adult flea beetles, which appear to be Redheaded Flea Beetles (cranberry flea beetle) feeding on foliage of mums. Shiny black beetles are about 3/16 -1/4” long with a reddish head (in good light). Antennae are light colored near the head and dark near the tips. Adults feed primarily on young foliage (mostly at night), chewing holes and causing leaf spot damage primarily on the upper surface of the foliage.
Flea beetles (Red Headed Flea Beetles) can be an occasional pest on chrysanthemums and herbaceous perennials. Shiny black beetles (about 3/16 -1/4” long) with a reddish head (in good light) feed primarily on young foliage, chewing holes and causing leaf spot damage. Symptoms are similar to four-lined plant bug injury, but the flea beetle spots are more irregular in shape.
Tobacco budworm feeds on buds and petals of geranium, calibrachoa and petunia. Tobacco budworms are generally a pest of home gardens and landscapes. However, adult moths can enter greenhouses with rollup sides, and lay their eggs on geranium or petunia buds. Caterpillars feed at night on flower buds, so that flowers fail to open. Petals may also be chewed. Fecal droppings may also be evident.
Potato aphids are common on ornamental plants. The potato aphid is pink or green (in this photo), with a darker stripe down its back (seen in related photo). Antennae are longer than their bodies, with long, black tipped cylindrical cornicles. This photo shows potato nymphs, shed skins and parasitized aphids. As aphids increase in size they shed their exoskeletons (cast skins) which are white and light weight. These white cast skins are often mistaken for whiteflies. The parasitized aphids (aphid mummies) appear as small brown swollen aphids.