This Month in Mid-Atlantic Horticultural News
Mid-Atlantic Horticultural Rolodex
Greenhouse Growers Conference held at Rutgers EcoComplex
By BILL PERSSON
In the middle of June, just before the start of summer, the New Jersey Nursery and Landscape Association held its Greenhouse Growers Conference at the Rutgers EcoComplex in Bordentown, N.J., which has research and business start-up greenhouses as part of the facility.
The conference is a new educational program for NJNLA. The first conference was held last year and was the beginning of an intended recurring event dedicated to providing education and updates for growers utilizing greenhouses and hoop houses.
NJNLA is a not-for-profit commercial horticulture trade organization, which originally began in 1915, 99 years ago.
After comment from Dominick Mondi, NJNLA executive director, the program started with a talk by Doug Barrow, a biological crop protection specialist with Biobest. Biobest provides biological pollination (bumblebees) and biological pest control, including beneficial insects, mites, nematodes and biopesticides. Barrow’s talk, “Incorporating Biological Control into Your Greenhouse Operation,” discussed the importance of understanding the life cycle and behavior of pests, and the effect of climate and other conditions, in order to choose the appropriate biological control agent, and to determine the timing of application.
Barrow concentrated his talk on four pests well-known in greenhouse operations – thrips, whitefly, aphids, and the two-spotted spider mite (TSSM). Identifying the particular species of a pest was indicated since some parasites may only be effective on a specific species.
He emphasized knowing where the pest is in its life cycle because some biological control agents may be effective only during a specific stage of the cycle. Barrow identified the four aphid species most prevalent in greenhouse operations – potato aphid, green peach aphid, black melon or cotton aphid and foxglove aphid.
A.J. Both, from the Department of Environmental Sciences at Rutgers, discussed “Light Emitting Diode (LED) Lighting for Greenhouse Crops.” He began with an overview of the light spectrum and then discussed why plants need light and how they use it.
While photosynthesis is the main use plants make of light, Both listed other processes that light affects in plants – including photoperiodism (the response to day length), photomorphogenesis (how light affects shape and growth), phototropism (the movement of plants in response to light, such as the sunflower, which turns toward the sun), and photodormancy (some seeds need light or dark to germinate – it is also a mechanism for plants which allows them to germinate or withhold germination based on light conditions – this can mean waiting for the right ecological conditions or for when competition will be reduced).
Both emphasized PAR – photosynthetically active radiation – the wavelength of light that plants use for photosynthesis (400 to 700 nanometers). He compared the various light sources used in greenhouses (incandescent, fluorescent, high pressure sodium, metal halide and LED), including their historic greenhouse use and their output wavelengths. One particularly interesting use of LED lighting was in vertical arrays in close proximity to the plants (intra-canopy) – only feasible because of the relatively low heat output of LED lamps.
For horticultural applications, Both suggested the use of a quantum sensor, which can measure the 400 to 700 nm (PAR) wavelength, and of a pyranometer, which can measure the full spectrum of solar radiation (280 to 2,800 nm) and also the angle of incidence – which is important for deciding on greenhouse structure and placement to get the most from natural light.
An additional instrument, the spectroradiometer, can graph light intensity on one axis and wavelength in nanometers on the other axis and display it on a laptop via a USB connection.
Dr. George Wulster, retired Rutgers Floriculture Extension Specialist, discussed “Plant Growth Regulators: An Integrated Approach.” During his talk, Wulster discussed what plant growth regulators are most useful for, and also when to not use PGRs as a substitute for good growing and plant management practices.
He also reviewed application techniques and the use of particular compounds for achieving specific results. Wulster said the use of PGRs should be done in conjunction with standard greenhouse growing controls such as nutrition, light, water, temperature and humidity.
Yasmin Rivera, post doctoral associate at Rutgers, reported on downy mildews on ornamental crops. After a technical description of downy mildews, including their life cycle, Rivera discussed the symptoms and management of impatiens, sunflower, coleus and basil downy mildews. Management techniques include choosing resistant varieties, facility cleanliness, air circulation and a preventive fungicide program.
There were additional presentations on new herbicides and fungicides, greenhouse marketing, and pesticide compatibility when used with biological control agents – especially when pollinating bees are present.