Organic Day Neutral Strawberry Scouting Report for June 30, 2023
This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Monday, June 30th in the morning. Field conditions during collections were hot, humid, and smoky.
This project aims to evaluate the effects of four different film-based mulches (black, white, and reflective plastic mulches, and paper mulch) on strawberry production in an annual, day-neutral system. This system-wide field trial is evaluating yield, fruit quality, pest pressure, and economic feasibility of this regionally novel system for strawberry production. Our field was planted on the 8th of May, and plants are still developing with flowers and runners removed as they appear, with runner removal continuing indefinitely and flower removal continuing until the first week of July. We are irrigating for short intervals several times a week, with fertigation occurring once weekly at the rate of 5 lbs N per acre.
Sampling Methods: 160 plants (40 plants per mulch treatment) were randomly selected and assessed for insect pest and disease presence and respective pressure using the University of Wisconsin Extension BioIPM Strawberry Workbook. At each sampling point, two leaves per plant were tapped into a white tray, and any thrips or tarnished plant bugs were counted. Mites were assessed on an incidence-basis: plants were evaluated for mite presence on older foliage and crowns. Each plant was also inspected for foliar disease symptoms. Declining or dead plants are removed and assessed in the laboratory for biotic causal agents.
Two-spotted spider mites: The incidence of two-spotted spider mitesstabilized this week at 52% of sampled plants this week. Only the oldest one or two leaves of affected plants were infested,
Beneficial Insects: This week, we also sampled 10 plants across our field for the incidence of beneficial insects including predatory mites (Fig 1), lady beetles, and Orius bugs. These insects are known to eat and manage spider mite and aphid populations. Ladybug larvae were present on 70% of sampled plants, while predatory mites were identified on 50% and Orius spp. on 30%.

Mite Management: The presence and amount of beneficial insects can be used to inform decisions about pest management; for example, a ratio of one predatory mite per 10 spider mites is often considered adequate for biological control. Chemical interventions can reduce the population of these listed natural enemies that control pest populations. Finally, the current patterns of infestation on 1-2 older leaves per plant does not seem to indicate an imminent threat of economic damage to our crop at this time. We are currently sampling the oldest leaves on each plant; if we decided to instead randomly sample both young and old leaflets, our observed incidence would likely be much lower, and below the recommended spray threshold of 25% incidence. Taken together, the significant presence of natural enemies in our field and the low perceived potential for economic damage have informed our decision to not spray for spider mites at this time. For more information on mite management, please refer to this article.

Thrips and Tarnished plant bugs: The amount of thrips increased slightly this week, while the amount of tarnished plant bugs decreased. These values have fluctuated slightly over the past month given local weather and harvest patterns. Next week will be our last week of flower removals, which will introduce a new (and tasty) food source for these pests. We will begin tapping flower clusters to sample for both insects in the week following next.
Incidental Insects: During scouting, we observed several red-headed flea beetles (Systena frontalis) (Fig 2) on the outer leaves of strawberry plants, and minor associated damage on leaves. We will begin to monitor their presence and damage in upcoming scouting.
Date | Mites (Incidence) | Thrips (Average per leaflet) | Tarnished Plant Bug (Average per leaflet) | Spotted- wing Drosophila (Incidence) |
6/9/2023 | 0.21 ± 0.064 | 0.07 ± 0.07 | 0.03 ± 0.03 | 0 |
6/15/2023 | 0.21 ± 0.064 | 0.13 ± 0.1 | 0.01 ± 0.01 | 0 |
6/26/2023 | 0.51 ± 0.08 | 0.09 ± 0.07 | 0.20 ± 0.07 | 0 |
6/30/2023 | 0.52 ± 0.08 | 0.17 ± 0.10 | 0.06 ± 0.04 | 0 |
Disease: During scouting this week, we noted two Phomopsis leaf blight (Phomopsis obscurans) lesions on mature leaves (Fig 3). Each affected plant has only one or two lesions, indicating early stages of infection.

Date | Common Leaf Spot | Phomopsis Leaf Blight | Verticillium Wilt | Anthracnose | Leaf Scorch | Neopest- alotiopsis |
6/9/2023 | 0 | 0 | 0 | 0 | 0 | 0 |
6/15/2023 | 0 | 0 | 0 | 0 | 0 | 0 |
6/26/2023 | 0 | 0 | 0 | 0 | 0 | 0 |
6/30/2023 | 0 | 0.01 ± 0.2 | 0 | 0 | 0 | 0 |
Funding for this project was provided by USDA-NIFA ORG award # 2021-51106-35490.
This article was posted in Berries and tagged Ariana Abbrescia, Christelle Guédot, DNS, DNS Organic, Jarret Miles-Kroening, Leslie Holland, Organic Day-Neutral Strawberry Production, organic strawberries, Strawberries.