Inspect Incoming Plants

January 27, 2016

Teach employees to inspect incoming plants as they arrive and before plants are moved into production areas. Look for the presence of insects, mites, diseases, and cultural problems such as nutritional deficiencies. If feasible, quarantine infested or problematic plants in an isolated greenhouse or area so they can be treated before they are placed in production areas. Here are a few tips for inspecting incoming plants:

Aphids –Look for aphids along plant stems, tips of new growth and undersides of leaves. Distorted new growth and white cast skins are signs of aphids.

Thrips –Inspect incoming plants for adults and larvae by tapping the new growth over a sheet of white paper. Typical symptoms of thrips feeding damage are distorted new growth and white scarring.

Fungus gnats– Look for emerging adult fungus gnats around the media surface.  Use potato slices to monitor fungus gnat larvae. Examine daily. Adults may emerge after watering dry pots.

Two-spotted spider mites - Look on the undersides of leaves, especially along the mid-vein for spider mites and their eggs on ivy geraniums, ipomea, thunbergia, dracaena, cordyline and other susceptible plants.  Symptoms are stippling or light flecking on the leaves. On ivy geraniums, spider mite damage is similar to damage caused by thrips and edema.

Broad mites – Look for symptoms:  Leaf edges of new growth curl downward, bronzing on undersides of leaves, hardened, distorted or twisted new growth and stunted growing tips.  Key host plants include dahlias, begonias, gerbera daisies, peppers, New Guinea impatiens and geraniums. Broad mites are very small so microscopic examination is often needed to confirm their presence.

Root health - Roots should be white with vigorous growth; brown, decayed roots are evidence of root rot disease or root death due to overwatering or high salt levels.

When handling and cleaning incoming plants, work in blocks and wash hands thoroughly between blocks of plants. If disposable gloves are worn, change or clean them between blocks. This will prevent spreading infectious diseases that are transmitted mechanically, such Bacterial leaf spot on geraniums and Tobacco Mosaic Virus (TMV) on petunias and related crops.

Tina Smith, UMass Extension and Leanne Pundt, UConn Extension

Resources:

Tips on Scouting Spring Ornamental Plants, (Slide show with photos) (UConn Extension)

Scouting Guidelines and Biological Control Options (Chart) (UConn Extension)

IPM Scouting and Decision Making (Fact sheet with video- located at bottom of page) (UMass Extension)