This will be the final scouting report for the year. Thanks for a great season!

This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Thursday, September 28th in the morning. Field conditions during collections were cloudy and warm.

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.

For spotted wing drosophila sampling, 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.

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
9/28/2023	0	0	0.16 ± 0.06	0.16 ± 0.06	0	0.03 ± 0.02

Tarnished plant bugs: The number of tarnished plant bugs increased again this week, but did not reach the economic threshold for spraying (25% of flower clusters). Adults and nymphs were both found on 16% 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. While TPB numbers continue to increase slowly, we anticipate colder weather and a reduction in fruit production over the next few weeks. We do not anticipate the need for another spray as the strawberry and TPB seasonal cycles come to an end.

This week, flea beetles were observed on 3% of samples. Red-headed flea beetles (Fig 1) seem to be most prevalent in the field, though flea beetle damage is still minor and not impacting production. Two-spotted spider mites and thrips were not observed during the scouting.

We did not find any Spotted wing drosophila larvae during our salt float tests this week. Paper wasps and yellow jackets are still feeding on rotting fruit in the field, though there appear to be fewer this week. We also found our first slug (Fig 2) this week! The slugs seem to prefer the moist microclimates of berries hanging in the clover-filled aisles, but they are not causing significant damage.

Orius bugs were found on 2 of 10 samples plants this week, while lady beetles were found on 1 of 10 plants. 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
9/28/2023	0.04 ± 0.03	0.07 ± 0.04	0	0	0	0	0.12 ± 0.05

This week, foliar diseases including Common leaf spot (Mycospharella fragariae) and Phomopsis leaf blight (Phomopsis obscurans) were found on 4% and 7% of sampled plants, respectively. Symptoms are minor, and do not seem to be impacting plant vigor.

Black root rot was found on 12% of samples this week, with a few extra plants showing the beginning signs of collapse.

The incidence and severity of Anthracnose (Colletotrichum fragariae) (Fig 3A) and Botrytis gray mold (Botrytis cinerea) (Fig 3B) have greatly increased. The cool, wet, weather conditions, as well as the unpicked infected berries left in the field this week likely contributed to this outbreak. On Monday 10/20/2023, berries with anthracnose or gray mold made up 1/3 of our total harvested fruit weight, reducing potential yield by up to 40%. A week prior (9/25/2023), before the rains and remaining inoculum, rotten fruit made up only 13% of total fruit weight, and reduced yield by just 18%.

Several steps can be taken to prevent and reduce the spread of anthracnose in strawberry production. Selecting reduced risk, disease-free plants and resistant cultivars can prevent the introduction of anthracnose into a field. Once established in a field, one of the most important cultural management techniques is to remove infected fruits and plant debris. The importance of this strategy can be demonstrated in our own field; over the course of one week, the percentage of rotten fruit increased by nearly 400% in the unpicked half of the field, while it increased by just 150% in the picked half of the field where rotten fruits were removed. The following steps can also be taken to prevent the development and spread of anthracnose:

• Avoid over-fertilizing
• Avoid over-irrigating and opt for drip irrigation when possible
• Do not work with plants when wet, and work with diseased plants last

More information about the organic chemical management of anthracnose and other strawberry diseases can be found in this publication.

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.