A new research project conducted by graduate student Jarret Miles-Kroening is looking at growing day-neutral organic strawberries in the Midwest. A major limitation growers face in transitioning to organic strawberry production is linked to the perennial matted row production system almost exclusively used in Upper Midwest states for strawberry production. The perennial nature of this system increases weed, insect, and disease pressure over multiple seasons that are challenging to control with current organic practices. The overall goal of this project led by Amaya Atucha, Christelle Guédot, Leslie Holland and colleagues at the University of Minnesota is to increase organic strawberry production by transitioning from a perennial to an annual production system using day-neutral strawberry. This change in production system would allow growers to maintain shorter, more diverse rotations, which in turn have been shown to decrease perennial weed, insect, and disease pressure. Reducing these horticultural challenges will hopefully encourage organic transition. The objectives of this research project are to: 1)determine plant growth, yield, and fruit quality of day-neutral strawberries grown in four film-based mulches; 2) determine the impact of film-based mulches on insect pests and pollinators in strawberries; 3) Evaluate the pressure of insect pests and diseases in day-neutral strawberry systems from planting to harvest; and 4) Estimate the break-even prices and farm-level profitability for organic day-neutral strawberries under low and high pest pressure.

A planting of day neutral organic strawberries (Fig. 1) was established in spring 2022 at the West Madison Agricultural Research Station with 16 x 60 feet rows randomized with four types of mulches: black polyethylene (AgResource, Chicago IL), white on black polyethylene (AgResource, Chicago IL), metallic reflective poly mulch (Imaflex USA, Thomasville NC), and creped paper mulch (WeedGuardPlus™).  The planting is managed with organic practices. For the third objective of this project, we are scouting for insect pests weekly during the season to assess which species are present and to determine if their numbers meet the established action thresholds that would trigger the use of an insecticide. We apply standard grower practices and refer to the BioIPM Strawberry Workbook for scouting methods. Scouting began in early June and each week we scout 5 plants per row in 12 rows for a total of 60 plants. For our scouting, plants are tapped over a plastic bag and bag contents are brought back to the lab, identified, and counted.

In the last three weeks, the scouting accounted for some two-spotted spider mites (Fig. 2), aphids (Fig. 3), and Eastern flower thrips (Table 1). We also observed some leafhoppers, a couple green caterpillars feeding on the plants, a small number of tarnished plant bug, and thousands of tiny springtails jumping around on the mulch. The springtails feed on decaying matter and are ubiquitous in the soil, causing no damage to strawberry plants. Overall, the numbers recorded with the tapping method yielded low numbers and, in the last three weeks, none of the insect pests recorded reached economic thresholds. For action thresholds, we use 25% of sampled plants with mites for two-spotted spider mites and 2-10 thrips per flower or small fruit for Eastern flower thrips. No insecticide was applied to the strawberries.

Table 1. Mean number ± SEM of weekly sampling for insect pests in day neutral strawberry.

Insects	6/15/2022	6/22/2022	06/28/2022
Mites	0.22 ± 0.11	0.01 ± 0.01	0.08 ± 0.05
Thrips	0.16 ± 0.09	0.03 ± 0.03	0.05 ± 0.04
Tarnished plant bug	0	0	0
Spotted-wing drosophila	0	0	0

Thank you to Rachel O’Neill Lewis for scouting the plants.

Happy growing season!

This article was posted in Berries, Insects and tagged berry, Christelle Guédot, day-neutral strawberry, DNS, DNS Organic, organic, Organic production, organic strawberries, strawberry.