Penn State Extension Specialists and Educators from across the state discussed the following issues currently being seen on farms in Pennsylvania during their recent bi-weekly conference call:
General conditions: Less rain, more heat, crops are finally moving along. We saw some beautiful product (leafy greens, green onions) coming out of high tunnels this spring. Some early field plantings of pumpkins have had to be replanted. We are now moving into harvesting of field-grown cabbage, zucchini and yellow squash. Several growers have sweet corn in dry tassel; quite a few will have sweet corn by July 4th.
ONIONS
Allium leaf miner is abundant in eastern and central PA, but has not yet been found in western PA. Damage is being found in onions, spring onions, and garlic. Damage to bulbs will occur where the larvae have established. Growers will need to cull infested bulbs during and after harvest. In some cases growers may be able to harvest early, peel off affected layers, and sell as fresh onions. While there is no efficacy data due to the recent arrival of this pest, systemic insecticides such as Exirel and/or Scorpion may provide some control if applied to infested onion and garlic plantings soon, as the odds of control decreases as the larvae move further into the bulbs, or secondary rots occur. Also, systemics may not work against pupae, and much of the population is already in the pupal stage. An update with photos can be found here: http://extension.psu.edu/plants/vegetable-fruit/news/2017/allium-leafminer-spring-update-may-30-2017. Hail damage was reported on some onions in south-central PA. Soft rots are setting in following hail damage.
VINE CROPS
Cucurbit downy mildew is moving up the east coast with new reports in Georgia as well as North and South Carolina. Aside from one report on watermelon in southern GA, all the recent reports have been on cucumber. The recent weather patterns have not put the mid-Atlantic region at risk. Remember that the pathogen that causes cucurbit downy mildew does not survive overwinter unless on living plant tissue. So for Pennsylvania growers, the pathogen is typically moving in via long-distance transport from other infected fields sometimes over 100 miles away. Awareness of where potential sources of the pathogen exist and forecasted weather conditions can help guide in-season management decisions. For the latest information on outbreaks and to receive email or text alerts please visit the Cucurbit Downy Mildew Forecasting website (http://cdm.ipmpipe.org/index.php). Updates will also be made to the 1-800-PENN-IPM hotline weekly or more frequently if needed to provide growers with information that can be used to help make timely management decisions. The forecasted risk maps are also based on knowing where there are downy mildew infected fields (sources of the pathogen) so it is important if you suspect downy mildew on your farm to let Beth Gugino know either by email at bkgugino@psu.edu or by phone at 814-865-7328, or contact your local Penn State Cooperative Extension Office.
Cucumber beetles are very active in most areas of the state. In one area, spotted cucumber beetles seem more abundant than the common striped cucumber beetle. Some growers are questioning if they are seeing resistance to pyrethroid insecticides with striped cucumber beetles.
TOMATOES, PEPPERS and POTATOES
Bacterial canker: it’s not just on tomato. There have been several pepper samples submitted to the Plant Disease Clinic that have tested positive for Clavibacter the causal agent of bacterial canker. On pepper, it can cause a marginal necrosis similar to tomato and can easy to distinguish from bacterial spot based on fruit symptoms. On the fruit, the spots are very white in color with a tan center as opposed to the dark corky lesions caused by bacterial spot. Management recommendations are the same as for other bacterial diseases on tomato and pepper with sanitation throughout the production cycle from seed to field being the most critical. More information on management can be found here: http://extension.psu.edu/plants/vegetable-fruit/news/2015/bacterial-spot-of-tomato-biology-and-management.
Also: Tomato russet mites and two-spotted spider mites have been causing problems in greenhouse and high tunnel tomato crops. The late blight type symptoms observed on potato in eastern North Carolina were determined to be caused by Phytophthora nicotianae and not late blight. This is probably the result of the history of tobacco production in the region. Late blight was confirmed in a very limited area in one field on the eastern shore of Virginia and determined to be US23. Timber rot was found in a high tunnel in northeast PA. Be on the lookout for blackleg and soft rot type symptoms in potato fields. The previous wet weather coupled with the recent hot temperatures is increasing diseases development.
SWEET CORN
Sweet corn pheromone trapping has begun, with European corn borer and corn earworm reports from parts of Pennsylvania and New York. For growers relying on Bt sweet corn varieties, be aware that use of these varieties should control European corn borer, but may not provide sufficient control of corn earworm or fall armyworm.
BERRIES
Strawberries: Harvest has been in full swing over the past week. Weeds have been a major challenge. Strawberry leaf scorch, common leaf spot, and phomopsis leaf blight have all been found recently in strawberries. Some berries have been misshapen due to spring frost damage.
Blueberries: There are several reports of oddly misshapen berries with this crop as well, probably due to weather factors.
From Penn State Extension