Despite a quick start to the spring, soil temperatures remain low across the much of the state. Average soil temperatures (3-inch depth) have been hanging around the mid 60s in central NJ and many warm-season weeds such as crabgrass have hardly developed despite germinating over 6 weeks ago. This crabgrass at our research facility has not […]
Archives for May 2017
May 25, 2017 A.Wyenandt, W.Kline, and J.Ingerson-Mahar
Potato | Tomato Disease Forecast 5-26-17
Click to View | Download Report 5-26-17
Potato Disease Forecasting Report
We will be tracking DSVs for Late blight development and calculating P-days for initiating the first early blight fungicide application.
The first late blight fungicide application is recommended once 18 DSVs accumulate from green row. Green row typically occurs around the first week in May in southern NJ. An early season application of a protectant fungicide such as mancozeb (Dithane, Manzate, Penncozeb) or Bravo (chlorothalonil) as soon as the field is accessible is suggested. Please be vigilant and keep a lookout for suspect late blight infections on young plants. No late blight has been reported in our region to date.
Remember the threshold for P-days is 300! Once 300 P-days is reached for your location, early blight fungicide applications should be initiated. Growers who are interested in using this model should choose the location above that is closest in proximity to their farming operation and should regularly check the Cornell NEWA website (http://newa.cornell.edu) where this information is compiled from. Click on Pests Forecasts from the menu, select your weather station, and click on tomato diseases, set accumulation start date, and a table of daily and total DSVs will be generated.
Tomato Disease Forecasting Report
Disease severity values (DSVs) for early blight, septoria leaf spot, and tomato anthracnose development are determined daily based on leaf wetness (due to rainfall, dew) and air temperature.
On a daily basis DSV values can range from 0 to 4 where 0 = no chance for disease development to 4 = high chance for disease development. DSVs are accumulated during the production season.
Fungicide applications are based on an individually determined DSV threshold. The first fungicide application for the control of these three diseases is not warranted until 35 DSVs have accumulated from your transplanting date. After that, growers can base fungicide applications on different DSV thresholds.
Reports generated by Ryan Tirrell
Rutgers, The State University of New Jersey
May 24, 2017 Kris Holmstrom and Joe Ingerson-Mahar
Veg IPM Update: Week Ending 5/24/17
Sweet Corn
Warmer weather has resulted in the first consistent European corn borer (ECB) catches. The highest catches have occurred in southern Hunterdon County (see map at 
left), although there have been low, but steady catches elsewhere, including northern Cumberland and central Morris counties. As yet, feeding has been very limited, with only single-digit infestation rates on whorl corn found in Mercer County. With continued moderate temperatures, expect feeding in whorl stage corn to increase significantly over the next week. Check 5 plants each in 10 random locations for a 50 plant sample. Look for “shot-hole” injury (see photo at right), and consider treating when the number of infested plants in a 50 plant sample exceeds 12%.
The highest nightly ECB catches for the previous week are as follows:
| Sergeantsville 4 | Denville 1 |
| South Branch 3 | East Vineland 1 |
| Allentown 1 | Eldora 1 |
A few corn earworm (CEW) continue to appear in blacklights throughout the state. These individuals indicate that there was limited overwintering of this pest in NJ, but are of little concern in the absence of silking sweet corn.
Cole Crops
IPM personnel continue to observe infestations of crucifer flea beetle. These beetles can build to high populations quickly, especially where wild mustard and related cruciferous weeds are common. Extreme feeding on small transplants can cause irreversible damage if not controlled promptly. [Read more…]
Fruit IPM Update for 5/24/17
Peach
Tufted Apple Budmoth (TABM): The first of 2 flights of tufted apple budmoth have started. Adults started to emerge in northern counties on 5/16 and in southern counties on 5/1. Although this has been a minor pest, timings are outlined below for anyone who had high populations last year. [Read more…]
May 23, 2017 Cesar Rodriguez-Saona
Whiteflies on Cranberries – How Much Should I Care?
Adult whitefly found in cranberries
Cranberry growers have faced a few challenges lately with “new” insect pests. I call them “new” because they have been around for many years but not in numbers high enough to cause any economic damage in commercial beds. This situation changed in the past few years when toad bugs and a mirid (both native to New Jersey) appeared in high numbers in a few cranberry farms in New Jersey. Since then, my message to cranberry growers has been to become more vigilant when scouting for insects. Being more vigilant comes with a price- you will start to see more “things” and become more concerned on whether what you see can be pests (i.e. reduce your yield). For instance, we have commonly seen thrips, whiteflies, and aphids in cranberry beds, sometimes in very high numbers. However, these insects have NEVER been reported as serious pests of cranberries. This doesn’t mean we should ignore them but simply not to be too concerned (lose sleep over them) at the moment. Since I joined Rutgers U., we have been scouting several beds for insects both detrimental and beneficial using different methods including sweep nets, sticky cards, and visual counts. We have commonly observed thrips and whiteflies in our yellow sticky cards. Despite being in high numbers, we have never seen a decrease in yield due to these insects. Recently, a grower reported high whitefly (adult) populations in his farm. Adult whiteflies are very small, whitish insects (white wings, yellow body; see picture); hard to see with the naked eye. Most species are polyphagous, meaning that they feed on several hosts. They have sucking mouthparts that allow them to feed on the plants’ juices (phloem). Whiteflies are most important for the transmission of diseases in plants but this is not the case in cranberries- no viruses have been linked to whiteflies in cranberries. They can also weaken plants by their direct feeding. Most cranberry growers likely had them in their farms for decades; yet, we have never seen any indication that they cause any damage to the vines or reduce yield. Interestingly, in a sweep net sample from late May, we observed high numbers of adult whiteflies but very few nymphs (immatures). This may indicate that adults are migrating from hosts other than cranberries; whether they overwinter in cranberries is unknown. We have collected adult whiteflies and will be sending specimens for identification. We will also conduct studies in the future to correlate whitefly numbers with yield. At this point, however, my message to growers is continue to be vigilant but not to be too concerned about whiteflies on cranberries.
May 22, 2017 A.Wyenandt, W.Kline, and J.Ingerson-Mahar
Potato | Tomato Disease Forecast 5-23-17
Click to View | Download Report 5-23-17
Potato Disease Forecasting Report
We will be tracking DSVs for Late blight development and calculating P-days for initiating the first early blight fungicide application.
The first late blight fungicide application is recommended once 18 DSVs accumulate from green row. Green row typically occurs around the first week in May in southern NJ. An early season application of a protectant fungicide such as mancozeb (Dithane, Manzate, Penncozeb) or Bravo (chlorothalonil) as soon as the field is accessible is suggested. Please be vigilant and keep a lookout for suspect late blight infections on young plants. No late blight has been reported in our region to date.
Remember the threshold for P-days is 300! Once 300 P-days is reached for your location, early blight fungicide applications should be initiated. Growers who are interested in using this model should choose the location above that is closest in proximity to their farming operation and should regularly check the Cornell NEWA website (http://newa.cornell.edu) where this information is compiled from. Click on Pests Forecasts from the menu, select your weather station, and click on tomato diseases, set accumulation start date, and a table of daily and total DSVs will be generated.
Tomato Disease Forecasting Report
Disease severity values (DSVs) for early blight, septoria leaf spot, and tomato anthracnose development are determined daily based on leaf wetness (due to rainfall, dew) and air temperature.
On a daily basis DSV values can range from 0 to 4 where 0 = no chance for disease development to 4 = high chance for disease development. DSVs are accumulated during the production season.
Fungicide applications are based on an individually determined DSV threshold. The first fungicide application for the control of these three diseases is not warranted until 35 DSVs have accumulated from your transplanting date. After that, growers can base fungicide applications on different DSV thresholds.
Reports generated by Ryan Tirrell
Rutgers, The State University of New Jersey
