In this issue
§ Scouting for insects: Aphids
§ Scouting for diseases: Botrytis blight
§ Uniform watering
§ Temporary wage poster available online
Aphids use their
piercing-sucking mouthparts to withdraw fluids from terminal growth and leaf
undersides. This results in leaf curling or distortion. Aphids produce
honeydew, a clear, sticky liquid. Aphids feeding on plants outdoors are
susceptible to many beneficial insects (natural enemies), including parasitic
wasps, ladybird beetles, green lace-wings and hover flies. Many species of
aphids feed on a wide variety of herbaceous perennials.
Management. A hard water spray will quickly remove aphids from plants and minimally affect any beneficial insects. Avoid overfertilizing and overwatering plants. Remove weeds from adjacent areas – many weeds serve as a reservoir for aphids. Contact and systemic insecticides may be effective in controlling aphids.
Pathogen. Botrytis cinerea.
Hosts. Very large host range, some of the most susceptible include Delphinium, Hosta, Iris, Lilium, Primula, Rudbeckia and Viola. Blossoms are especially susceptible.
Symptoms. Seedling blight, leaf spots and blight, distortion of young leaves, crown rot and blossom blight.
Signs. In high relative humidity, grayish, fuzzy mold on the surface of the affected tissue is visible with the naked eye.
Spread. Spores are produced in mass under humid conditions and are readily released and moved by air currents. Additionally, overwintering structures (sclerotia) are formed and can persist in soil and plant debris. Sclerotia are found on the surface of heavily diseased plant material.
Management. Sanitation and aeration procedures that reduce humidity levels around plants and appropriate fungicide applications are recommended for disease control. Botrytis cinerea can sporulate on dead plant material; fallen leaves and petals should be carefully removed from production areas. Trash cans used for dead plant tissue should not be kept in production areas. Regular fungicide applications will likely be necessary to reduce losses on especially susceptible hosts grown in humid environments.
Is your crop uniform from end-to-end and side-to-side in each house? If plants are smaller at one end, it usually means a temperature difference from end-to-end. However, while side-to-side differences can be due to temperature, check your booms or overhead watering system. I’ve noticed more than a few partially plugged nozzles this spring, usually due to buildup of calcium carbonate or calcium bicarbonate. The growers are usually puzzled by the buildup because they are adding acid to reduce bicarbonate in their water, but, when asked, admit that they hadn’t tested their water this spring and were adding the same amount of acid as last year. When this season’s test came back, the bicarbonate levels were significantly higher and the amount of acid needed to be increased. Be aware that drops in bicarbonate can also cause problems even if your nozzles don’t plug. Low bicarbonate levels increase the probability of sudden pH drops because there is little buffering, so acid sensitive crops such as geraniums can be at risk.
Another reason for non-uniformity in watering is worn out nozzles. Water is abrasive, and even ceramic nozzles wear out eventually. I can’t determine flow rates by looking, and even small differences in flow from nozzle-to-nozzle can influence plant growth, especially when the weather warms up. It’s too late to check your nozzles after the crop shows differences, so take a little time now to put containers under each nozzle, run the system for a short time and then measure the variation in the amount of water applied.
With the changes in the minimum wage, I noticed that some greenhouses still have the old poster for minimum wage laws from the Department of Labor & Economic Growth posted with incorrect information.
With all the changes, the Department of Labor & Economic Growth has approved a 8 ½” x 11” sheet that will temporarily replace your wall poster until new posters are printed and available. Just print off this copy and replace your old wage poster. (Now you will be in compliancy for notification.) Click here for the temporary sheet.
If you have been out of the loop, here is the current wage and the proposed wages that will take affect July 1, 2007. Last October 1, 2006, the minimum wage for employees increased to $6.95 per hour if you employ more than two employees. On July 1, 2007, the wage will increase to $7.15 per hour.