EVALUATION OF FUNGICIDES FOR WHITE PINE BLISTER RUST CONTROL ON BLACK CURRANT, 2004

Authors: Turechek, William; MCKAY, S - CORNELL; HEIDENREICH, M - CORNELL; HEIDENREICH, G - CORNELL

Submitted to: Fungicide and Nematocide Tests
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2005
Publication Date: 4/1/2005
Citation: Turechek, W., Mckay, S.A., Heidenreich, M.C., Heidenreich, G. 2005. Evaluation of fungicides for white pine blister rust control on black currant. Fungicide and Nematocide Tests. 60:SMF020.

Interpretive Summary: White pine blister rust is a perennial rust of 5 needle pines, most importantly the white pine, and an annual rust of currants and gooseberries. The fungus causing the disease requires both hosts to complete its life cycle. In the early 1900s, several states in the Northeast passed legislation prohibiting the cultivation of susceptible black currant varieties to minimize damage to the white pine, a mainstay of the timber industry. Today, the use of white pine as lumber is rare, but the antiquated ban on producing black currant remained in effect until recently. New stands of black currant are being planted throughout the Northeast and growers are now in need of fungicides to protect their crop from white pine blister rust. However, few fungicides are labeled for use on black currant for control of this disease. We tested 14 fungicides for their ability to control the disease on black currant and to develop the data necessary to request label expansion. Seven of the fourteen fungicides provided very good to excellent control of white pine blister rust and warrant label expansion. The results of this trial will help growers gain access to needed fungicides as they begin to explore the new market niche and economic opportunity that is currently being fostered as processors anticipate growers diversifying in to black currant production.

Technical Abstract: White pine blister rust, caused by the fungus Cronartium ribicola, is a perennial rust of 5 needle pines, most importantly white pine (Pinus strobus), and an annual rust of currants and gooseberries (Ribes spp.); both hosts are needed to complete its life cycle. In the early 1900s, several states in the Northeast passed legislation prohibiting the cultivation of susceptible Ribes spp., particularly black currant (Ribes nigrum), to minimize damage to the white pine, a mainstay of the timber industry. Today, the use of white pine as lumber is rare, but the antiquated ban on producing black currant remained in effect until recently. The lifting of the ban, however, has produced an upsurge of protests from professional foresters and 'nature enthusiasts' that consider white pine as an important native of eastern forests, and they are deeply concerned of the adverse effects white pine blister rust may have if susceptible black currant varieties are permitted to be planted. In an effort to develop improved management tactics for white pine blister rust, a field trial was designed to evaluate the efficacy of 14 fungicides against white pine blister rust on black currant. The trial was conducted in a mixed planting of black currant, red currant and gooseberry in Geneva, NY, and fungicides were applied regularly from late April through harvest in July. The results showed that programs incorporating the sterol-inhibiting fungicides Nova and Indar, the EBDC fungicide Dithane, and the copper-based fungicide Kocide provided superior control. The organic products Serenade, Citrex 100L, Elexa 4 PDB and JMS Stylet oil, while providing significant levels of disease reduction, were not as effective as the conventional products. Oxidate provided no control. The results of this trial will help growers gain access to needed fungicides as they begin to explore the new market niche and economic opportunity that is currently being fostered as processors anticipate growers diversifying in to black currant production.