Organic Day Neutral Strawberry Scouting Report for July 7, 2023
This scouting session for our day-neutral organic strawberry project at the West Madison Agricultural Research Station (WMARS) was conducted Friday, July 7th in the morning. Field conditions during collections were sunny 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 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. After 07/07/2023, thrips and tarnished plant bugs were 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.
Two-spotted spider mites: The incidence of two-spotted spider mitesremains stable at 52% of sampled plants this week. We noticed a few spider mites dropping into our tray during leaflet-tapping, indicating that mites are present on upper leaves. Despite this, no associated mite damage has been observed on these new and upper leaves. The dry weather is very conducive to mite outbreaks which can explain such high incidence. Please refer to this article for more information on mites.
Predatory Mites: 6 of 10 sampled plants had predatory mites. These mites can be more difficult to identify than our other scouted insects, and are characterized by their longer legs, lack of spots, and faster movement than the two-spotted spider mites that they predate. Predatory mites can provide good biological control of two-spotted spider mites if left untreated. A good way to see if you have enough predatory mites to control the two-spotted spider mites is to count the number you see on leaves. A ratio of one predatory to 10 two-spotted spider mite would indicate that you should obtain adequate control. Because of the lack of injury from two-spotted spider mites and the presence of predatory mites on 60% of the plants, we are not anticipating to spray for two-spotted spider mites this week.
Lady beetles: 5 of 10 sampled plants contained lady beetle larvae and/or adults (Fig 1A). Lady beetles are beneficial insects and should be conserved in agroecosystems to allow them to prey on pest insects such as aphids. For more information on lady beetles, please see the article on them in this issue.
Orius bugs: 6 of 10 sampled plants had Orius bugs, many of which were insidious flower bugs (Orius insidiosus) (Fig 1B). Orius bugs are also known as minute pirate bugs and they are also biological control agents that feed as immatures (nymphs) and adults on pest insects such as aphids, leafhoppper nymphs, thrips, spider mites, insect eggs and small caterpillars. Orius will insert its beak inside the host body, while immobilizing its prey with its front legs, and suck on the insect insides until it is dried up.


Thrips and Tarnished plant bugs: Thrip and tarnished plant bugs counts decreased this week, though both were notably present on our in-field sticky cards. Next week will mark the beginning of our flower cluster tapping when scouting for these insects, which may alter our observed amounts.

Flea Beetles: This is the first week we scouted for flea beetles (Fig 2), which were observed on a whole-plant basis. We observed nearly 1 flea beetle per 10 plants, with a few plants showing associated damage on upper leaves.
Japanese Beetles: We noticed several japanese beetles feeding on strawberry leaves in the field this week. These beetles seem to be feeding primarily on smartweed leaves in the aisles, and are moving to strawberry leaves where the weeds are touching. For more information on Japanese beetle, please visit this article.
Date | Mites (Incidence) | Thrips (Average per two leaves* or one flower cluster) | Tarnished Plant Bug (Average per two leaves* or one flower cluster) | Spotted- wing Drosophila (Incidence) | Flea Beetle (Average per plant) |
6/9/2023 | 0.21 ± 0.064 | 0.07 ± 0.07 * | 0.03 ± 0.03 * | 0 | 0 |
6/15/2023 | 0.21 ± 0.064 | 0.13 ± 0.1 * | 0.01 ± 0.01 * | 0 | 0 |
6/26/2023 | 0.51 ± 0.08 | 0.09 ± 0.07 * | 0.20 ± 0.07 * | 0 | 0 |
6/30/2023 | 0.52 ± 0.08 | 0.17 ± 0.10 * | 0.06 ± 0.04 * | 0 | 0 |
7/07/2023 | 0.52 ± 0.08 | 0.05 ± 0.05 * | 0.03 ± 0.03 * | 0 | 0.09 ± 0.05 |

Phomopsis leaf blight (Phomopsis obscurans): The incidence of phomopsis leaf blight increased from 1% to 8% of sampled plants this week. Infected plants appear to be in early stages of infection, with 1-2 total lesions per plant. Phomopsis obscurans is a fungal pathogen of strawberry plants that primarily affects the leaves (Fig 3), but can also cause lesions on stems and fruit. This pathogen is often introduced on transplants or nearby susceptible plants and spreads via splashing water. As such, wet conditions often favor pathogen development and spread. Overall, field conditions to-date have been too dry to favor the rapid spread of this disease, along with many others that rely on leaf wetness and splashing water. We also observed two Common leaf spot (Mycospharella fragariae) lesions on our sampled plants, and will continue to monitor for the development and spread of symptoms.
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 ± 0.02 | 0 | 0 | 0 | 0 |
7/07/2023 | 0.01 0.02 | 0.08 ± 0.04 | 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, day-neutral strawberry, DNS, DNS Organic, Jarret Miles-Kroening, Leslie Holland, Organic Day-Neutral Strawberry Production, Strawberries, strawberry.