Vegetable - Small Fruit Production Issues: August 2, 2018

The last weeks of July drenched Pennsylvania - as many as eight to 10 inches of rain were recorded in some areas. Growers need to be watching for flooding in their fields, and the inevitable spread of vegetable diseases with this warm, wet weather as we go into August.

Vegetables

Colorado potato beetle has been observed on potatoes in Pennsylvania - it is important to note that the greatest damage to plants is by the late instar larvae and adults. These insects are best controlled with crop rotation and no-till management, but current infestations can be sprayed with proper insecticides.

Both squash bug and squash vine borer were found on squash plants recently. Any squash plants that appear to be wilting should be examined for squash bug - they will often attempt to hide behind stems and leaves. The squash vine borer is usually not spotted until after the damage is done. As with all boring insects, sprays need to be timed to contact the insects before they bore into the plant. Cucumber beetles are still active in many cucurbit fields - foliar insecticides may be needed to keep them under control. Angular leaf spot has also been confirmed on squash and cucumber this week.

The fungus Septoria leaf spot was found on tomato this week - when infected, the plants appear to wither from the bottom up. Bacterial diseases have also arrived - both bacterial canker and speck were identified on tomato as well as bacterial leaf spot on pepper. These diseases are best when prevented with both heat-treated seed and equipment sanitation. The video Scouting and Identifying Tomato Diseases will refresh your memory on scouting for and identifying tomato diseases. Insects have popped up on tomato in high tunnels - both thrips and silver leaf white fly have been found this week. Using sticky cards is an important component of scouting for insects in high tunnels.

White mold in snap bean was identified - growers should adopt an integrated approach to management, including crop rotation and chemical or biological control. Mexican bean beetle has also been spotted on beans - most damage is caused by the larvae feeding on the leaves, flowers, and pods of the plant. Control these insects with biocontrol or insecticides.

Recent sap beetle infestations in sweet corn are causing significant post-harvest losses. These scavenger beetles feed on developing, ripe, or overripe produce - keep the production area as clean as possible by picking in a timely manner and removing damaged, diseased, and overripe produce.

Sap beetle larva in corn. Photo: Shelby Fleischer, Penn State

Blueberries

While we're not seeing very high numbers of spotted wing drosophila yet in Pennsylvania, many neighboring states are reporting high numbers. Now is a good time to review how to identify and control this invasive pest.

PestWatch Report on August 1, 2018

Corn earworm (CEW) counts are rising throughout PA. Counts spiked (reached 3-4 day thresholds, averaging >100/week) in Blair, Erie, and Washington Counties, and continue at 4-5 day thresholds in Fayette county. Additional sites reached or approximated a 5-6 day threshold, either this week or last, in Blair, Centre, Clinton, Erie, Indiana, Lehigh, Montgomery, Montour, and York counties. The upward trend noted last week has continued, spread throughout much of PA, and dramatically increased in multiple locations. This upward trend is most obvious by scrolling the time bar at the bottom of the online PestWatch map from about the middle of June to August 1. If you have multiple plantings, the plantings in fresh silk will be most attractive. Moths will also lay eggs on drying silk. Silking corn should be protected, and when counts are very high, Bt-cultivars may also require a single spray to achieve very high rates (>95%) of clean ears.

European corn borer (ECB) counts at the localized hot spot in Clinton county is rising, perhaps suggesting the 2nd generation. The hot spot in York county also increased. All other sites are low.

Fall armyworm (FAW) spiked in Erie County and is picking up in Centre and Lycoming counties.

In summary, the upward trend in CEW counts is now occurring throughout most of PA and spiking in at least 3 locations. ECB adult flight is localized in a few hot spots, and suggest the beginning of a 2nd generation. FAW spiked in Erie and is rising in a few additional sites.

Thresholds

Reproductive (tassel/silk) and late vegetative corn attracts moths. Shorten spray schedules when populations increase. If CEW is not a problem, then consider ECB.

Current Trap Counts

Average weekly catch – a moving average for the last 7 days. The average catch per night (catch, divided by the number of nights trapping), divided by the number of nights where data exist, multiplied by 7. Weeks where all the average-catch-per-night values are nulls are treated as if no data exist for that week.

Corn earworm