IR-4 Ornamental

16 Feb

The Ornamental Horticulture Program was started in 1977 to address the disease, insect, and weed management tool and plant growth regulator needs of growers. Over time this program expanded to cover not only ornamental horticulture plants grown in greenhouses and nurseries, but landscape plantings, Christmas tree farms, sod farms and interiorscapes ( Here are some updates. For more ornamental summary reports, click

Fusarium Efficacy Summary

From 2001 to 2011, numerous products representing 24 active ingredients were evaluated in greenhouse and field trials as soil drench, foliar, in-furrow, drip irrigation or tuber soak applications against several Fusarium species causing rots (crown, stem and tuber rots) and wilt on ornamentals, and wilt and root rot on vegetables. Fusarium species tested included: F. avenaceum, F. communi, F. oxysporum and F. solani. Most trials were conducted on F. oxysporum on larkspur, lisianthus and watermelon. Although there were insufficient data for definitive conclusions, several relatively new products showed promising, though inconsistent, efficacy comparable to the standards. These include acibenzolar, Heritage (azoxystrobin), Compass (trifloxystrobin), Hurricane (fludioxonil+mefenoxam), Insignia (pyraclostrobin), SP2169, Tourney (metconazole) and Trinity (triticonazole). BW240, (Trichoderma harzianum & T. virens), CG100 (organic acid), Pageant (boscalid+pyraclostrobin) and Palladium (cyprodinil+fludioxonil) provided no to mediocre efficacy. Proline (prothioconazole) provided consistently good control of F. oxysporum in watermelon trials. The established standards 3336 and Medallion generally provided inconsistent efficacy while Terraguard was effective in one trial. What do we do about this? Selection (plants), scouting and rogueing.

Bacterial Disease Efficacy Summary

From 2008 to 2010, 46 products were tested through the IR-4 Program as drench or foliar applications against bacterial pathogens. Species tested included: Erwinia amylovora, E. chrysanthemi, P. chicorii, P. marginalis, P. syringae, Pseudomonas sp., Xanthomonas campestris and Xanthomonas spp. In general, all products, including the standard copper containing bactericides (Camelot, CuPRO, Cuprofix, Cuprofix MZ, Junction, Kocide, Phyton 27 and ReZist) and mancozebs (Dithane, Penncozeb, Protect) and biologicals (Cease, Rhapsody), provided variable efficacy on these bacterial pathogens. Several new products that are included in the 2010 Bacterial efficacy project looked promising based on their efficacy relative to standards. These include Acibenzolar, CG100, Citrex, HM-0736, Kasumin, Regalia, SP2015 and Taegro. Further research is needed to obtain additional efficacy data to recommend actions to register or amend labels for these pests.

Early Post Emergent Efficacy Summary

From 2008 through 2011, fourteen pre-emergent herbicides were tested across the United States through the IR-4 Ornamental Horticulture Program to determine whether they can control emerged weeds at the cotyledon to 1 leaf or 2 to 4 leaf stage. Three troublesome weeds were targeted initially including bittercress oxalis and spurge with Eclipta and Phyllanthus added later. Bittercress (Cardamine sp.) was controlled at the early postemergence application timings with Certainty at 0.035 and 0.094 lb ai/A, EXC3898 at 2.1 and 3.1 lb ai/A, Gallery 75 DF at 1.0 lb ai/A and V-10142 (imazasulfuron) at 0.38 and 0.75 lb ai/A. Emerged oxalis (Oxalis sp.) seedlings showed significant impact with early postemergence applications of Casoron 4G at 4 lb ai/A, Certainty at 0.035 and 0.094 lb ai/A, Gallery at 0.5 and 1.0 lb ai/A, indaziflam at 50 and 100 g/ha, SureGuard at 0.562 lb ai/A, Tower at 0.97 lb ai/A and V-10142 0.75 lb ai/A applications. Spurge (Chamaesyce sp.) control was demonstrated at early postemergence timings with 1.5 lb ai/A of Tower and 4.0 lb ai/A of Pendulum. Limited experiments with Broadstar 0.25G and Broadstar VC1604, FreeHand, and HGH-63 showed promise on at least one of these weed species. Additionally, eclipta (Eclipta sp.) was found to be controlled in limited testing by Casoron 4 (lb ai/A), Certainty (0.035 and 0.094 lb ai/A), SureGuard (0.383 lb ai/A), Tower (0.97 and 1.94 lb ai/A) and Basagran (1.0 lb ai/A) when applied early postemergence. Phyllanthus (Phyllanthus sp.) was also controlled by these products with the exception of Basagran. These findings benefit growers by identifying select preemergence herbicides which control specific weeds at early emergence stages in container grown ornamental horticulture crops.


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