Allen D. Owings | 1/19/2010 2:41:26 AM
For successful greenhouse crop production, growers must be able to recognize symptoms of insect, disease or nutritional problems in their plants and take corrective measures before major crop losses occur. Although scouting regularly does give you the added benefit or early detection, it is essential to employ practices that improve overall greenhouse management. For that purpose, we have taken the liberty of compiling some best management practices (BMPs) that we hope will reduce the chance of symptoms on your plants that need to be interpreted.
Cuttings taken from stock plants that have insect or disease problems bring problems into your greenhouse from day one. If you purchase your cuttings, make sure they come from reliable reputable sources with certified clean stock programs. While growing your plants from seed does reduce risk to some degree, many pathogens are disseminated on seeds, including – but not limited to – Alternaria, Rhizoctonia, Phytopthora, Xanthomonas, Psuedomonas, cucumber mosaic virus and tobacco ringspot virus. If possible, quarantine new plants in an isolated greenhouse until it can be confirmed that plants are healthy.
Just because the source you used in the past has a great reputation for quality and you have an excellent track record with them in the past does not guarantee that your latest order will be pest free. Examine your new plants closely to avoid bringing another nursery’s problem into your greenhouse.
You paid for the equipment you are growing your plants in; use it correctly. Know the light level our crop requires and provide it. Reduce problems with diseases like downy and powdery mildew by providing adequate ventilation. Select equipment such as benches that have impermeable surfaces so they can be easily cleaned and sterilized. Make sure your benches and floors are even. This will reduce puddling in your greenhouses, reducing the occurrence of Pythium root rot.
Eliminate all weeds and remove all pet plants. Weeds are often the source of viruses such as impatiens necrotic spot virus and tomato spotted wilt virus.
Removing weeds by physical and chemical means often reduces the occurrence of insects in your greenhouses. Weeds serve as both food and home for insects that will often invade your greenhouse through ventilation ducts.
It is extremely important to test the accuracy of your fertilizer equipment every two to three months to ensure your plants are getting the proper nutrition. Test more frequently if crops indicate a problem or dye color indicates irregularity.
A program that minimizes the effect of a troublesome factor, such as high or low bicarbonate, should be implemented and strictly followed.
The most effective equipment for pesticide delivery disperses small droplets uniformly, allowing easy penetration of the plant canopy. Choose systemic materials that compensate for incomplete coverage. Using sticky strips or cards, monitor efficacy.
Minimize use by using long-term insecticide rotations, using insecticides with non-specific modes of action and avoiding persistent application. Use the least toxic pesticide available that will do the job, and stay abreast of university trials that compare product performance. This is particularly useful in the case of new materials.
This is as simple as common sense and some general housekeeping. Never place plants, pots, hoses or flats on contaminated surfaces. Disinfect used pots before reusing them by soaking in a 10% bleach solution and then rinsing. Expeditiously move plants that have disease symptoms or heavy insect infestations into an area where they can be destroyed without causing further contamination. After removal, clean hands and change clothing to prevent the spread of insects or diseases to other sections of the greenhouse.
When observations are made, record them for future reference. Additionally, record when fertilizer, pesticide or herbicide applications are made. Include chemicals used, amounts, volume delivered and application equipment used. This information will prove valuable over time.