This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Thursday, September 14th in the afternoon. Field conditions during collections were sunny and hot. 

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 (Incidence)	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

There were very few insect pests in the field this week, likely due to the recent Pyganic spray and the progression of the season.

Tarnished plant bugs: This week, the number of tarnished plant nymphs dramatically decreased. Only two adults were observed across the scouted samples, and nymphs were found on only 4% 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 anticipate that the TPB have reached the end of their seasonal cycle, and do not intend to spray Pyganic again.

This week, thrips were observed on 3% of samples. Two-spotted spider mites and flea beetles were not observed during the scouting. Beetle injury continues to appear in the far end of the field (Fig), with Japanese beetles causing the most damage, though to a limited extent. Japanese beetles are also reaching the end of their seasonal life cycle and should not cause any significant injury at this time.

Orius bugs were found on 1 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

Foliar diseases including Common leaf spot (Mycospharella fragariae) and Phomopsis leaf blight (Phomopsis obscurans) persist in the field, and were found on 13% and 9% of sampled plants, respectively. Symptoms are minor; lesions are isolated to older leaves, and often appear as secondary infections on the leaves of collapsing plants.

Black root rot was found on 10% of samples this week. We have not noted significant collapse in the field since last week’s heat wave.

Berries with Anthracnose (Colletotrichum fragariae) were present again this week during harvest, with notably worse symptoms on infected fruit (Fig 2). In several berries, lesions covered over 50% of the fruit surface. 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.