This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Thursday, September 21st in the morning. Field conditions during collections were partly sunny, hot, and humid. 

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 having ceased the week of July 3rd. Routine harvests began the week of July 24, and have continued through the season. 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. Since 07/07/2023, thrips and tarnished plant bugs have been sampled by tapping one flower cluster per sampled plant into a tray. 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.

Insect Pests:

Table 1. The incidence and average number of insects observed per plant in day-neutral strawberries during weekly sampling.

Date	Mites (Incidence)	Thrips (Average per two leaves* or one flower cluster)	Tarnished Plant Bug Adults (Average per two leaves* or one flower cluster)	Tarnished Plant Bug Nymphs (Average per two leaves* or one flower cluster)	Spotted- wing Drosophila (Average per strawberry)	Flea Beetle (Average per plant)
6/9/2023	0.21 ± 0.06	0.07 ± 0.07 *	0.03 ± 0.03 *	0	0	0
6/15/2023	0.21 ± 0.06	0.13 ± 0.1 *	0.01 ± 0.01 *	0	0	0
6/26/2023	0.51 ± 0.08	0.09 ± 0.07 *	0.20 ± 0.07 *	0	0	0
6/30/2023	0.52 ± 0.08	0.17 ± 0.10 *	0.06 ± 0.04 *	0	0	0
7/07/2023	0.52 ± 0.08	0.05 ± 0.05 *	0.03 ± 0.03 *	0	0	0.09 ± 0.05
7/14/2023	0.35 ± 0.08	0.04 ± 0.05	0.21 ± 0.09	1.09 ± 0.15	0	0.09 ± 0.04
7/21/2023	0.14 ± 0.08	0	0.10 ± 0.05	0.29 ± 0.09	0	0.04 ± 0.03
7/28/2023	0.03 ± 0.02	0.01 ± 0.01	0.14 ± 0.07	0.28 ± 0.09	0	0.05 ± 0.04
8/04/2023	0	0.02 ± 0.02	0.19 ± 0.07	0.04 ± 0.03	0	0.01 ± 0.01
8/11/2023	0	0.01 ± 0.02	0.26 ± 0.08	0.11 ± 0.06	0	0.01 ± 0.02
8/18/2023	0	0.01 ± 0.01	0.13 ± 0.05	0.39 ± 0.09	0	0.01 ± 0.01
8/25/2023	0	0.09 ± 0.05	0.14 ± 0.06	0.44 ± 0.12	0	0.02 ± 0.02
8/30/2023	0	0.02 ± 0.02	0.16 ± 0.07	0.57 ± 0.12	0	0
9/08/2023	0	0.01 ± 0.01	0.16 ± 0.06	0.38 ± 0.09	0	0.01 ± 0.02
9/14/2023	0	0.03 ± 0.02	0.01 ± 0.02	0.04 ± 0.03	0	0
9/21/2023	0	0.01 ± 0.02	0.08 ± 0.04	0.13 ± 0.05	0.03 ± 0.03	0.01 ± 0.02

Tarnished plant bugs: The number of tarnished plant bugs increased this week, but did not reach the economic threshold for spraying (25% of flower clusters). Adults were observed on 8% of flower clusters, and nymphs were found on 13% of flower clusters.

We have sprayed Pyganic 1.4 EC on 7/17/23, 7/25/23, 7/31/23, 8/16/23, 8/21/23, 8/31/23, and 9/13/23 this season. For more information on our decision to spray and methods, please refer to this past article. We will continue to scout and monitor pest presence for the rest of the season, but anticipate that the TPB have reached the end of their seasonal cycle.

This week, thrips and flea beetles were observed on just 1% of samples. Two-spotted spider mites were not observed during the scouting.

We currently have many yellow jackets (Fig 1A) feeding on older fruit in our field. The damage they cause is mostly opportunistic; they bore holes into large, softened strawberries, scraping away at the fruit in groups of 2-4. The damage associated with these pests is not widespread, but they can be a nuisance during harvest. More information on wasp damage in fruit systems can be found in this article. This week, we also observed a Chinese mantis (Fig 1B) hunting in our field. These predators are often generalists, meaning that they will eat a variety of insects. This can include pollinating bees, flies, and beetles, as well as grasshoppers, wasps, and moths.

This week, we also had our first confirmed observations of Spotted wing drosophila larvae (Fig 2). Each row is tested by lightly crushing ten fruits in a ziploc bag and adding a saltwater mixture (1 cup of salt per gallon of water) to cover the berries. After letting sit for one hour, the water is drained into a coffee filter and scanned for fruit fly larvae. Five larvae were found in only one row sample this week, so incidence does not appear to be widespread yet. We will continue to test for drosophila larvae weekly, and will provide updates here.

Orius bugs were found on 2 of 10 samples plants this week, while lady beetles and predatory Mites were not present on the 10 randomly selected plants.

Diseases:

Table 2. The incidence of diseases observed per plant in day-neutral strawberries during weekly sampling.

Date	Common Leaf Spot	Phomopsis Leaf Blight	Verticillium Wilt	Anthracnose	Leaf Scorch	Neopest- alotiopsis	Black Root Rot
6/9/2023	0	0	0	0	0	0	0
6/15/2023	0	0	0	0	0	0	0
6/26/2023	0	0	0	0	0	0	0
6/30/2023	0	0.01 ± 0.02	0	0	0	0	0
7/07/2023	0.01 ± 0.02	0.08 ± 0.04	0	0	0	0	0
7/14/2023	0.01 ± 0.01	0.06 ± 0.04	0	0	0	0	0
7/21/2023	0.01 ± 0.01	0.07 ± 0.04	0	0	0	0	0
7/28/2023	0	0.08 ± 0.04	0	0	0	0	0
8/04/2023	0	0.06 ± 0.04	0	0	0	0	0
8/11/2023	0	0.08 ± 0.04	0	0	0	0	0
8/18/2023	0	0.09 ± 0.05	0	0	0	0	0
8/25/2023	0.02 ± 0.02	0.09 ± 0.04	0	0	0	0	0
8/30/2023	0.02 ± 0.02	0.04 ± 0.03	0	0	0	0	0.06 ± 0.04
9/08/2023	0.11 ± 0.05	0.09 ± 0.04	0	0	0	0	0.09 ± 0.05
9/14/2023	0.13 ± 0.05	0.09 ± 0.05	0	0	0	0	0.10 ± 0.05
9/21/2023	0.05 ± 0.03	0.06 ± 0.04	0	0	0	0	0.09 ± 0.05

This week, foliar diseases including Common leaf spot (Mycospharella fragariae) and Phomopsis leaf blight (Phomopsis obscurans) were found on 5% and 6% of sampled plants, respectively. This is a lower incidence than last week, perhaps because older leaves are senescing/dying as the season progresses. Symptoms continue to be isolated to one or two older leaves, and do not appear to be impacting plant vigor.

Black root rot was found on 9% of samples this week, with no notable progression in symptoms in the past week.

Berries with Anthracnose (Colletotrichum fragariae) (Fig 3A) continue to appear during harvest. Symptoms seem to be worsening with recent wetter conditions; several berries have shown near-complete surface lesions. We also noted Botrytis gray mold (Botrytis cinerea) on one berry this week (Fig 3B). We are anticipating an increase in fruit diseases with the upcoming wet and cool weather. More information about fruit rots of strawberry can be found in this article, while fungal foliar diseases can be found here.

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, day-neutral strawberry, DNS, DNS Organic, Jarret Miles-Kroening, Leslie Holland, Organic Day-Neutral Strawberry Production, organic strawberries.