Plants on display in your garden center or farm stand require regular, gentle watering to maintain high quality. Watering should be completed during the daylight hours, to allow plants to dry before dark. The drying will help prevent foliar diseases. If plants are to be watered by hand, be sure to furnish sufficient time and personnel to water thoroughly. Anything less, and plant quality will decline rapidly.
Place hanging baskets in areas beside the aisles, not over aisles where water and fertilizer will drip onto customers and create a hazard.
Tarsononemid mites including cyclamen mite and broad mite can cause serious damage to a wide range of greenhouse crops such as New Guinea impatiens, garden impatiens, dahlias, gerbera, ivy, lantana, snapdragon, verbena, zinnia, peppers and other vegetable plants.
Symptoms of bacterial leaf spot caused by Pseudomonas cichorii on basil appear as brown and black spots on leaves and streaking on the stems. The leaf spots are angular or irregular or delineated by the small veins. The bacterium has a wide host range and infects chrysanthemum, geranium, and many other ornamental and foliage plants but is not known to be host specific. P. cichorii can be present on asymptomatic plants allowing long distance distribution of the bacterium via propagative material. On basil, seed and infected plugs are the most likely sources of infection.
Tospovirus is a genus that includes Impatiens Necrotic Spot Virus (INSV) and Tomato Spotted Wilt Virus (TSWV). Western flower thrips is the predominant insect vector. Thrips acquire the disease as a first instar larvae as they feed on virus-infected plants (including infected weeds showing few, if any symptoms). Once mature, the winged adult thrips are primarily responsible for viral spread. An infected thrips is able to transmit tospoviruses to at least one plant per day until its death. Adults do not transmit the virus to their young.
Powdery mildew was reported on rosemary this week.
In addition to rosemary, the characteristic white spots of powdery mildew usually first appear first on the upper surfaces of the lowermost leaves of many types of plants such as non-stop begonias, calibrachoas, dahlias, asters, phlox, monarda and other susceptible crops. Stems and flowers may also become infected.