This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Friday, September 8th in the morning. Field conditions during collections were cloudy, cool, and breezy with misty rain. 

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

Tarnished plant bugs: This week, the number of tarnished plant nymphs decreased to 38% of flower clusters. Adults remained stable at nearly 1 in 5 flower clusters. While reduced, this week’s abundance of nymphs is still above the economic threshold of 1 in 4 flower clusters.

            Thus far this season, we have sprayed Pyganic 1.4 EC on 7/17/23, 7/25/23, 7/31/23, 8/16/23, 8/21/23, and 8/31/23. For more information on our decision to spray and methods, please refer to this past article. We plan to spray Pyganic again to control tarnished plant bug in response to their reduced but persistent presence, and anticipate this downward trend to continue as the season progresses and they reach the end of their seasonal cycle.

This week, two-spotted spider mites were not seen in the field. One thrips and two flea beetles were observed during scouting. An increase in flea beetle damage was noted in the far end of our field this week, and will continue to be monitored.

Orius bugs (Fig 1)and lady beetles were found on 2 of 10 sampled plants this week. Predatory Mites were not present on the 10 randomly selected plants. Pollinators were few and far between this week, perhaps in response to the extreme heat followed by very cool temperatures.

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

Following both last week’s heat wave and this week’s cool and wet fall weather, we are beginning to see more disease in the field. Foliar diseases including Common leaf spot (Mycospharella fragariae) (Fig 2A) and Phomopsis leaf blight (Phomopsis obscurans) (Fig 2B) increased this week to 11% and 9% of sampled plants, respectively. Symptoms continue to be minor; lesions are often isolated to 1-2 older leaves on each plant, and often appear as secondary infections on the leaves of collapsing plants.

Black root rot has persisted in the field, and incidence increased slightly this week. We expected this additional decline with the extreme heat over Labor Day weekend; additional abiotic stress like drought and heat can speed and worsen plant declines.

Berries with Anthracnose (Colletotrichum fragariae) and Botrytis gray mold (Botrytis cinerea) were not present during harvest this Friday, likely due to the extremely dry conditions earlier in the week. We expect to see more fruit diseases with the wet and cool weather ahead, and will provide updates here as they appear. 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.