Ornamental Outlook




The mission of OHP is to serve greenhouse and nursery professionals with effective products, exemplary service and to share our knowledge. A better educated customer is a better steward for the industry. We are proud to sponsor the OHP Ask the Expert page on the Greenhouse Grower and Ornamental Outlook web sites. On this page you can read answers to your insect and weed control questions, download past questions and answers, submit your questions and hear from OHP’s trio of experts – Richard Lindquist, Dave Barcel and Jeff Dobbs. Take advantage of the extensive resources available to you from OHP and bookmark this page!

May's QUESTIONS & ANSWERS

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This is a common situation for growers when sales are affected by poor weather or slow sales periods. "Holding over" plant material can be achieved by using Paczol sprays or sprenches. That said there are two important issues to remember. First, PGR’s applied to plants just setting flower buds may have a delay in bloom response. This delay can range from 3-7 days. Drench applications tend not to affect bloom response as much as sprays do. Second, the PPM dose for holding over crops can range from ½ ppm to 5 or 10 ppm. The rate will depend on the crop. A general rule would be to use one half of the normal spray rate used during finish for a spray application or approximately ½ to 5 ppm for a sprench application. Growers need to test these rates for their specific crops and growing conditions. Growers could also grow the plants "harder" by growing the plants at colder temperatures, increased spacing and less watering to slow down growth. For example on bedding plants a combination of 1000ppm B-Nine + 800ppm Cycocel gives a good delaying effect for about two to three weeks.			I was supposed to ship flats of bedding plants three weeks ago, but because of the weather I need to hold them in good condition for additional two weeks. What is the best way to keep these plants in prime condition for sales or shipment?

Yes, thrips have been problems. Not only must we deal with the western flower thrips (Frankliniella occidentalis) and relatives, but another recent addition to the thrips pest list is the chilli thrips (Scirtothrips dorsalis). The best way to manage thrips is to keep them from becoming well-established by scouting and monitoring, plus using an effective pesticide rotation program. Some of the products and tank mixes to include in the rotation are Pylon (greenhouse only), Conserve+Pedestal, Avid+Azatin and Naturalis O+Azatin. Marathon is very effective against the chilli thrips. More information on thrips control is available on www.ohp.com.			Thrips have been giving us fits this year. Do you have any suggestions for an effective thrips control program?

Discus Nursery Insecticide is a combination product containing the active ingredients in Marathon and Decathlon. As such, it is effective against a wide range of -- but not all -- insects. Scale insects -- especially some armored scale and mealybug species -- may not be effectively controlled with Discus alone. Grower experiences in Florida and elsewhere have shown that a combination of Discus and Talus (an insect growth regulator) is very effective against these insect pests. Also especially for scale or mealybug control, it is very important to include a good surfactant. Growers should test any surfactant-pesticide combination before large scale use.			I have been using Discus to control numerous insects in my nursery. Control of most of them has been excellent, but sometimes control of scales and mealy bugs is only fair. Do you have any suggestions?

Black root rot also known as Thielaviopsis basicola can be a major problem in some crops. Pansies come to mind, as does vinca. This disease can cause damage to the roots of plants with an appearance that is gray to black in appearance. These roots are now weakened and minimized in the ability to absorb nutrients. It is best to address any control of any disease early. And sanitation is always a factor. Look carefully at plugs before planting, and look for good white roots indicating a healthy plant. Greenhouse management of the essentials, such as temperature, moisture, soluble salts should always be monitored. An acidic pH of around 5-6 may minimize problems. Keeping plants vigorous and not stressed is a good way to prevent problems. Fungicides like OHP 6672 and Compass O are very effective in the control of Thielaviopsis basicola and work best as a preventative or at the first signs of infection.			What can I do to prevent black root rot?








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