As the popularity of alternative healthful and flavorful fruits has increased, growers are increasingly raising gooseberries for local markets.  Gooseberries can be used by small-scale processors in preserves and baked desserts and the fresh fruit are popular with some consumers.  Growers can select varieties and manage harvest timing to suit different markets: tart, underripe berries are well suited for many processing uses, and riper, sweeter, and highly flavored fruit are best for fresh eating.  In the Upper Midwest, we’ve found that prices typically range from $6-$8 per pint for fresh berries sold at retail and $4-$4.50 per pound for berries sold wholesale to processors. 

In the Upper Midwest, many growers have struggled to control Anthracnose leaf spot.  This troublesome fungal disease infects leaves repeatedly beginning in late spring, causing dark purple spots on the leaves, followed by massive defoliation as early as late June.  Over several years, defoliation presumably reduces plant health and yield.  Without access to synthetic fungicides, organic growers can be particularly hard-pressed to manage Anthracnose leaf spot.

Chris and Juli McGuire raise organic apples, currants, and gooseberries on their farm in Lafayette County, southwest Wisconsin.  Working with Leslie Holland at UW, we’ve just completed a two year on-farm research project evaluating organic methods for control of Anthracnose leaf spot.  In a replicated, quarter-acre field trial, we compared three techniques for disease control:

• Variety: We measured disease susceptibility of Black Velvet, Captivator, Hinnomaki Red, and Tixia.
• Trellising: We compared untrellised, bush plants to plants grown with the cordon trellis system, thinking that the trellised plants might suffer less disease because their sparse, narrow canopies would dry more quickly after dew and rain. 
• Organic sprays: We trialed three sprays allowed under the USDA organic standards: Cueva® (copper soap) tank mixed with Double Nickel 55™ (Bacillus amyloliquefaciens strain D747), Carb-O-Nator™ (Potassium bicarbonate), and Regalia® (Extract of Reynoutria sachalinensis), as well as an unsprayed control treatment.   Sprays were made every ten days from June through August.

We measured early season disease incidence in June as well as late-season defoliation.  Data collected in 2021 and 2022 showed clear, consistent patterns.  Of the four varieties, Hinnomaki Red was most resistant and Tixia was most susceptible.  However, disease resistance needs to be balanced with yield, flavor, and other factors.  Hinnomaki Red, for example, is in our experience a very small, compact plant that produces modest yields and is difficult to harvest, and therefore may not be desirable despite its disease resistance.

Trellising reduced disease by a small but significant amount.  Although trellising reduces disease, it may not be justified because of its high cost.  At Two Onion Farm, a trellised planting requires approximately $15,000 per acre in additional money for trellis materials and plants, as well as an extra 300 hour of labor per acre over the first two years of the planting.  To justify those extra costs, trellising needs to have very substantial benefits such as faster harvest and improved fruit quality.

Of the spray treatments trialed, Cueva® (copper soap) tankmixed with Double Nickel 55™ (Bacillus amyloliquefaciens strain D747) provided the most control, reducing early season disease and late season defoliation.  Regalia® (extract of Reynoutria sachalinensis) provided a significant reduction in early summer disease but did not affect late season defoliation.  Carb-O-Nator™ (Potassium bicarbonate) gave no control.   Growers will need to consider the materials and labor costs of spraying as well as the environmental impacts of repeated copper sprays.  If gooseberries are a minor crop on a diverse fresh market farm, they may not merit the attention needed for regular timely sprays.

This study did not reveal any methods of Anthracnose Leaf Spot control which were completely effective at eliminating the disease.  Anthracnose symptoms occurred in all experimental treatments.  However, we found clear and consistent evidence that variety selection, trellising, and organic sprays all provide some control of Anthracnose.  Growers will have to select the mix of control methods that best fits their operation.

A detailed report of our results and a video summary are available online at www.twoonionfarm.com/research/ and Chris is available to answer questions by email: twoonionfarm@gmail.com.

Disclaimer: This product was developed with support from the Sustainable Agriculture Research and Education (SARE) Program, which is funded by the U.S. Department of Agriculture – National Institute of Food and Agriculture (USDA-NIFA).  Any opinions, findings, conclusions, or recommendations expressed within do not necessarily reflect the view of the SARE program or the U.S. Department of Agriculture.  USDA is an equal opportunity provider and employer.

This article was posted in Berries, Disease and tagged Anthracnose, Chris McGuire, disease, gooseberries, Gooseberry, leaf spot, Leslie Holland, organic.