Strawberries

Black Root Rot found in strawberry plantings in the Mid-Atlantic this season.

Cyclamen mites have been found in a few Mary-land strawberry fields in the last few weeks. They are not much of a problem now but when we start to warm up, they may become more of a problem along with two spotted spider mites.

Strawberry Botrytis fruit rot, also called gray mold (fig 1), is a common disease that typically drives fungicide sprays throughout a season. Flowers are considered the gateway for the pathogen, and some flower infections can stay latent until the fruit ripens while some may show up earlier at green berry stage under wet and cool conditions.

Various sensors can be used to monitor environmental variables in fields, including ambient temperature, relative humidity, rain depth, wind speed, leaf wetness (LWD), soil temperature, and soil moisture. These can be critical variables for decision-making for crop protection or yield prediction. These data (namely ambient temperature and LWD) can also be useful for disease prediction models such as those used for Botrytis (BFR) and anthracnose (AFR) fruit rots of strawberry (Hu et al. 2021). A traditionally placed weather station at the edge of a field (see ‘elevated’ station below) may also not fully capture the conditions in the field. Floating row covers are a common tool in Mid-Atlantic strawberry fields for manipulating the crop microclimate for facilitating crop development under cold conditions and for protecting from freeze events. Therefore, covered strawberry plants should have a vastly different microclimate than would be reported from traditionally placed weather stations or non-covered plants. We evaluated differences in sensor readings based on placements either in the canopy or in the traditional, elevated setting. We also evaluated the effect of row covers on the sensor readings. Lastly, we evaluated how these different placements would affect disease prediction models utilized in a fungicide spray program.

With the cooler weather we have had of late I was surprised to find low levels of mites in strawberry fields, with a few hot spots of mites in some high tunnels. There were two species of mites found: the two spotted spider mite, Tetranychus urticae and the cyclamen mite Phytonemus pallidus.

Over the years I have seen dark spots on the foliage of strawberry plants like the ones in figs. 1 and 2. These spots can look pretty bad at times and are thought to possibly be the start of some disease such as angular leaf spot or anthracnose.

The cool, wet spring weather we have been experiencing favors slugs, so be on the lookout for slug damage. Slug damage may easily be confused for sap beetle feeding, but management of these pests is very different, so it is important to correctly identify the problem. Both pests can be common in matted row production. Authors: Sankara Ganesh, Maria Cramer, and Kelly Hamby, Department of Entomology, University of Maryland, College Park

Managing gray mold (Botrytis) on strawberries is increasingly challenging because of fungicide resistance development, plus a new Botrytis species that is less susceptible to fungicides is becoming common in the mid-Atlantic region. Resistance to certain fungicides is also a problem in management of anthracnose fruit rot. This article describes disease management strategies designed to slow further resistance development, while also providing specifics for managing our two most common fruit rots. Authors: Dr. Mengjun Hu, Univ. of Maryland, and Kathy Demchak, Penn State Extension

I visited some strawberry fields over the last few weeks in Maryland and while most of the fields were on plastic, some were matted row production. Overall I found low levels of mites in most of the fields, with a few hot spots.

Over the last few weeks I have been sent pictures of and have seen dark spots on the foliage of strawberry plants (figs. 1 and 2).