Page 12 - Griffin Gazette Issue 1 - 2019
P. 12

Make 2019
                                            THE YEAR OF…

                          Greenhouse Herb Production:
                          Keeping It Clean

                               By Rick Yates, GGSPro Technical Services Manager
                               Greenhouse production of herbs continues to increase in all of its
                               manifestations. Cell packs and small pots for planting into the garden, or
                               for “windowsill farming," have been joined by herbs grown on to harvest
                               by both hydroponic and traditional production techniques. Consumers
                               understandably have little or no tolerance for insects, mites or diseases
                               in their fresh herbs. Growers are challenged to meet that objective by the
                               fact that some herbs are particularly prone to such problems, while the
                               number of pesticides labeled for greenhouse herbs is relatively small. Add
                               to that the fact that some growers seek to be certified organic, making
                               threading that needle a little more challenging. So what’s a grower to do?
                               Let’s start with disease management. Even the best fungicides can fail
                               if we haven't first done all we can to optimize the growing environment
                               to discourage disease development. Sometimes overlooked is variety
                               selection. A good example would be downy mildew of basil, where
                               important breeding work is underway to produce disease-tolerant
                               varieties, such as the new Amazel basil from Proven Winners.
                               Herbs are often grown at a high density, which can sometimes backfire
                               when it comes to disease prevention. Tightly spaced crop canopies can
                               create microclimates of high humidity air in the crop which favor disease
                               development. This can also make applying the microbial fungicides that
                               are primarily contact products difficult to deliver to where they are needed
                               the most. Evaluate your crop spacing, especially for notoriously disease
                               prone herbs.
                               The  tried-and-true IPM  technique  of  scheduling  irrigations  to minimize
                               the length of time that the foliage stays wet should be employed as well.
                               Herbs grown in NFT hydroponic systems or in small pots on troughs
                               benefit from dry foliage and the ability to get air movement to the base of
                               the plants.
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