2022 PA Vegetable and Berry Current Issues for June 21

On tomato, this is often called zippering or catfacing on the fruit while on cucurbits, the blossom end may not fill completely to form a uniform fruit. This is often the result of a weather-related pollination issue that occurred earlier in the season. As spring comes to a close and we officially enter the summer season, spring temperatures across much of Pennsylvania averaged normal while precipitation varied from slightly above normal in the far western and eastern regions of the state to slightly below in the most northern and southern tiers. (Northeast Regional Climate Center).

Do You Have Aggressive Honey Bees?

In much of the northern U.S., beekeepers are not prepared to manage and work with highly defensive honey bees, which can pose a threat to beekeepers and the public. Without proper management plans or testing availability, beekeepers and the public may be injured or killed when working with or near these aggressive colonies. With support from the Pennsylvania Department of Agriculture (PDA), members of Penn State's Lopez-Uribe Lab and their collaborators are working to develop a reliable genetic protocol that would be available to beekeepers and apiary inspectors who may need to reliably test for the presence of defensive behavior in PA. With this information, we will develop a management plan to monitor and control these defensive bees.

We are looking to test and sample defensive colonies throughout Pennsylvania and need your help. We are interested in visiting colonies that chase you out of the beeyard, chase and sting people when the hive is not open or disturbed, and/or fly in your face and stick to the front of your veil, even when you use smoke. If you believe you have a honey bee colony that fits this description, please see our website Defensive Honey Bees in Pennsylvania, or contact us at lopezuribelab@gmail.com.

Field Production

Last week cucurbit downy mildew was confirmed in at least one commercial cucumber field in southern New Jersey. This is the time of year to regularly scout cucumber and cantaloupe fields. Please report if you suspect downy mildew. This disease is best managed on an areawide scale to reduce overall inoculum. Fungicides are currently the best management tool, and their timely application can effectively manage this disease.

Bacterial diseases of onion are becoming a common sight in fields as the temperatures increase and the onions start sizing up. These diseases are most likely to spread when the bacteria are splash-dispersed between plants during strong thunderstorms and high winds that can damage the plants. Copper-based fungicides tank-mixed with an EBDC fungicide such as mancozeb will help protect the uninfected plants but not stop the disease once it starts in the symptomatic plants.

Figure 2. Corn earworm begins feeding at the tip of ears and often leaves moist frass behind. Photo: Karly Regan, Penn State

Onion thrips are being reported in onions as well and should be managed once populations exceed one thrips per leaf. In addition to reducing photosynthesis, they can also increase the risk of bacterial bulb rot as their feeding creates easy entry points into plant tissue. Thrips can also feed on grasses, so movement into vulnerable vegetables often increases as small grains approach harvest time and hay crops are cut. Be sure to scout for them as hay is cut in your area.

Corn earworm trap counts have been increasing throughout the state and reached spray thresholds of 4- to 5-day intervals at sites in Blair, Franklin, Lehigh, Mifflin, and Washington counties. Corn that is tasseling or silking will be highly attractive to these moths, so be prepared to spray corn that has reached these growth stages. Since eggs are laid on silk, control via insecticides is best done through contact with the very young larvae before they move into the ear.

Many commonly occurring insects of vegetable crops are appearing, often in low numbers or in a few locations. Flea beetles are causing shothole damage to potato and eggplant. Spider mites are showing up in vine crops and strawberries. Spider mites often initiate populations in localized aggregations and thrive in hot, dry conditions. Sap beetles have been reported in strawberries and could move into sweet corn as ears begin to develop. Initiate sanitation (clean harvest, clean up fields after harvest) now to avoid sap beetle problems in corn later in the season.

Figure 3. Pale striped flea beetle adult (left), and characteristic shot hole damage (right). Photos: W. Cranshaw, Bugwood.org

Figure 4. Early spider mite feeding damage on vine crops will appear as yellow spots on leaves. Photo: Karly Regan, Penn State

Berry Crops

Now that strawberry harvest is winding down in much of the state, it is time to decide whether to carry over plantings or not. If you are growing ‘Chandler’, ‘Flavorfest’ or any other variety with any symptoms of Neopestalotiopsis, it is strongly recommended that the planting not be carried over. It is important to avoid having this disease become established in your fields or surrounding vegetation.

Figure 5. Symptoms of Neopestalotiopsis on leaves consist of large areas of the leaf being invaded and black pycnidia within the lesions. Photo: K. Demchak, Penn State

If you have carried over plasticulture plantings successfully in the past, and the plants look healthy this year, it is fine to keep them, but in general, we have seen increased winter injury, disease, insect pressure, and plant death in carryover fields. In matted-row plantings, the renovation process causes older plants to be replaced with new ones, so a quick decline in plant health is less likely than in plasticulture. The plant sources and varieties grown in matted-row fields in PA are different from those which have had Neopestalotiopsis issues; we have not been able to find this disease in matted-row fields in PA so far. Otherwise, it seems that strawberries have had every disease and insect issue possible this year, along with a compressed harvest season.

Injury from herbicide drift to each of our major berry crops has been reported. Hopefully, if a neighbor’s farm is involved, a reasonable conversation concluding in reaching an understanding will occur. However, if that is not the case, the article Herbicide Drift and Sensitive Plants: What to do if Drift is Suspected includes some steps to take.

Several growers have reported blueberry canes stems being loaded with fruit and having few leaves. In these cases, each bud on the cane was only floral, with few or no leaf buds present. This is occurring mainly in ‘Bluecrop’ which tends to overfruit if not pruned hard. It is likely that some combination of environmental conditions, plant stress, cane age, and variety have combined to cause this issue. Canes overloaded with fruit should be removed to encourage more new canes to grow to bring the plant back into balance, as younger canes are more vegetative. If there is an underlying source of plant stress (high pH, lack of mulch, lack of water, poor nutrition), this should be corrected. Heavier pruning of old canes may be needed in the planting in the future.

Figure 6. Fruit load imbalance on canes of ‘Bluecrop’. Photo: K. Demchak, Penn State

Scale insects have also been noted on some of these older canes, sometimes with crawlers present. Esteem (with a 7-day PHI) is an effective option to treat the crawler stage. Many of the broad-spectrum insecticides used for spotted wing drosophila are effective on crawlers, too, but also kill beneficials that may have been keeping the scale insects at bay.

Figure 7. Scale insects, unidentified as of this writing, in a split in blueberry cane bark. A tiny yellow crawler (in box) can be seen on the blueberry bark. Photo: K. Demchak, Penn State

Orange rust is being seen on black raspberries and blackberries. There is no cure for this disease, as it is systemic in the plant, so plants should be dug out after the tops are carefully removed to avoid dispersing spores. Category 3 and category 11 fungicides can help to protect other plants in the planting but will not cure the disease. There are other rust diseases that are not systemic that could be present, but orange rust causes much more extensive leaf symptoms than other rusts at this time of the year.

Figure 8. Orange rust pustules on blackberry leaf underside. Photo: K. Demchak, Penn State

As you are harvesting raspberry or blackberry plants that would have been tipped last summer, you may notice a hole in the cane pith at the tip of the cane. If this hole only extends a few inches downward, it is not caused by a borer pest, but instead is a hole made by an emerging solitary bee pollinator. Some solitary bee larvae may still be developing in additional chambers in the stem and could be mistaken for borer larvae.

Figure 9. Hole in tipped black raspberry cane from a solitary bee, not a borer pest. Photo: K. Demchak, Penn State

Spotted wing drosophila season is just around the corner. See the article Spotted Wing Drosophila: A 2021 Update for Berry Growers for more information and this accompanying table for efficacy ratings of insecticides and berry crops on which they may be used.

Plans are being made for the release of small numbers of a beneficial parasitoid (Ganaspis brasiliensis) that attacks Spotted Winged Drosophila in central and southeastern PA (as well as surrounding states), and for monitoring to determine its establishment this summer, fall, and next spring.