Populations of the cranberry toad bug, Phylloscelis rubra (Figure 1), have increased in the last week in some beds. In a recent study, we showed that even relatively low densities of this insect can cause significant injury to cranberries (Rodriguez-Saona et al. 2020. Characterizing the Feeding Injury Caused by Phylloscelis rubra (Hemiptera: Dictyopharidae) to Cranberries, Journal of Insect Science, 20 (6), 37, https://doi.org/10.1093/jisesa/ieaa143). Thus, monitoring for this insect from the end of July through mid-August is critical.

Figure 1. Cranberry toad bug

Life cycle. Cranberry toad bugs feed only on cranberries. This insect has a single generation per year (Figure 2). It overwinters as eggs. The nymphs appear by the end of June through early September, and the adults from end of July through October (harvest). Eggs are laid from end of August through October.

Damage. Feeding damage can be noticed in two stages. 1st-stage feeding damage on vines causes closing in (towards the branch) of the leaves on the new growth. 2nd-stage feeding causes changed in color (reddish to brown) of new growth. The damage can be seen from July until harvest. This damage will cause dying of the branch and the berries to shrivel up (Figure 3). Heavy infestation will result in dwarfed berries.

Management. To determine infestation, lightly sweep problematic beds (bugs should be easy to catch in sweep nets as they are very active). Currently there is no threshold established for this pest. Thus, insecticide applications should be based on the relative number of bugs per sweep compared with other sites and previous history of infestation. If needed, growers can use the following control options: Sevin 4F (broad-spectrum carbamate), Diazinon, Imidan 70W (broad-spectrum organophosphates), and Actara or Assail 30SG (neonicotinoid insecticides, effective against piercing-sucking insects). If infestation is high, treatments should be applied now (mid-August) for best control.

Figure 3. Cranberry toad bug injury

Figure 2. Cranberry toad bug phenology

Based on our degree-day (DD) model for Sparganothis fruitworm, first eggs hatched at about 895 DD (see chart). As of July 02, Sparganothis has accumulated 1101.5 DD (using April 15 as biofix). This indicates that eggs have started to hatch, and fruit will become susceptible to infestation since larval injury to fruit usually begins after the eggs hatch. According to our model, peak flight should have occurred about a week ago (on the week of June 20). Insecticide applications are usually recommended 10-14 days after peak flight (i.e., week of July 4). Most beds should be close to the end of bloom. If trap counts have been high, growers should consider treatment by next week (depending on the variety and time of winter flood removal) to prevent damage to berries. If spraying when bees are present, your option is to use an insect growth regulator (IGR), such as Intrepid, or the diamide Altacor. Our “standard” recommendation has been, however, to wait until bees are removed to apply an insecticide. Your post-bloom options include the organophosphate Diazinon, the diamides Altacor, Verdepryn, or Exirel, the spinosyn Delegate, or the IGR Intrepid. Timing of insecticide application is critical; so, if needed, do not wait too long to manage this pest.

Degree-day model for Sparganothis fruitworm

We would like to invite all NJ cranberry growers to the 2022 Cranberry Twilight Meeting to be held at the P.E. Marucci Center (Pole Barn) on Tuesday June 14. Pesticide credits will be available at the end of the meeting.

Agenda

5:30-6:00 PM Dinner

6:00-6:20 PM “Strategies for Early Detection of Crop Loss”
Dr. Peter Oudemans, Professor Blueberry/Cranberry Pathology, Rutgers University

6:20-6:40 PM “Update on Postemergence Weed Control Strategies for Cranberry”
Dr. Thierry Besancon, Assistant Extension Specialist, Weed Science, Rutgers University

6:40-7:00 PM “2022 Insect Pest Management Updates”
Dr. Cesar Rodriguez-Saona, Extension Specialist, Entomology, Rutgers University

7:00-7:20 PM “Systemic Diseases of Cranberry’”
Dr. James Polashock, Research Plant Pathologist, USDA-ARS

7:20-7:40 PM “Updates on the USDA-ARS Cranberry Breeding & Genetics Program”
Dr. Jeffrey Neyhart, Research Geneticist, USDA-ARS

7:40-8:00 PM “Beyond the Application: Precautions for Mixing and Loading the Pesticide Spray Tank”
Kate Brown, Program Associate—Commercial Agriculture, Rutgers Cooperative Extension of Burlington County

The information from this article was kindly shared by Lindsay Wells-Hansen (Sr. Agricultural Scientist, Ocean Spray).

As many of you might be aware by now, there are several formulations of the newly registered product Fanfare (bifenthrin) for which we have supplemental labels for use in cranberry. However, there has been a bit of confusion surrounding which of these products are actually registered for use in the state of NJ.

Currently, FANFARE ES (EPA Registration # 066222-0099) IS registered for use in NJ. The supplemental label can be found here (https://www.cdms.net/ldat/ldB3C000.pdf) and is valid until 12/21/2024.  Unfortunately, this formulation seems to be difficult to obtain from distributors at this time.

Fanfare 2EC (EPA Registration # 066222-0236) and Fanfare EC (EPA Registration # 066222-0261) are NOT registered for use in NJ at this time despite the fact that there are supplemental labels for cranberry for these products and it sounds like some local distributors are carrying the 2EC formulation of this product. Unfortunately, the 2EC and EC formulations CANNOT be used in NJ in 2022. The manufacturer is working on getting all formulations registered in NJ, so hopefully we’ll have more options available for use in the future.

I hope this helps to clear up some confusion surrounding bifenthrin products.

Blunt-nosed leafhoppers (BNLH) continue to be an increasing threat to cranberries in NJ. BNLH has one generation a year. It overwinters as eggs, which begin to hatch in early May. The nymphs (Picture 1) will go through five instars in about a month. The adults begin to appear by the end of June and are most abundant in mid-July. Numbers of this species start to diminish by the end of July. The adults have a characteristic blunt head and vary from light yellowish-gray to dark brown. Eggs are laid in June-July. Nymphs and adults get their food by sucking the plant juices of the cranberry vines with their piercing-sucking mouthparts. This direct injury is, however, not noticeable. They are most important as vectors of false blossom disease. Infected uprights produce sterile flowers (do not produce berries). Branching is stimulated in infected plants resulting in a witches’ broom. Foliage on infected plants might redden prematurely and fall.

Picture 1. Blunt-nosed leafhopper nymph. Photo by Elvira de Lange.

Here are some guidelines to consider when managing BNLH in cranberries:

1. The most important point in BNLH control is locating the sites of infestation. Monitoring for this insect is accomplished best with an insect sweep net. Nymphs should be monitored before bloom using sweep nets (this time of year). Nymphs before bloom are small; thus, ideally, you may need to freeze the samples (to kill them), and then count the number of nymphs under a microscope or using a magnifying lens.
2. To monitor, perform sweep sets of 25 sweeps each. The recommended number of sweep sets is: 1 per 1–10 acres, at least 10 sweep sets per 10–20 acres, and 1 sweep set per 2 acres for more than 20 acres.
3. A challenge for managing BNLH is the fact that they vector a phytoplasma that causes false blossom disease. For this reason, it is difficult to establish economic thresholds for this pest because we do not know the proportion of individuals that are infected in the population. Moreover, this proportion can vary depending on the variety. For instance, we have observed higher incidence of infection in the newer varieties even when populations of leafhoppers are low.
4. Although this needs to be tested, based on experience, I came up with the following tentative treatment thresholds:

– An average of 20 nymphs per sweep set if it is a new variety bed, bed with young plantings, and/or a bed that has a recent history of false blossom.

– An average of 40 nymphs per sweep set if it is an older bed and older variety with no previous history of false blossom.

5. If BNLH populations are increasing compared to previous years and the beds have not been treated for BNLH for 2-3 years, growers should consider treatment.
6. If growers have treated for BNLH in the previous year and populations are low (average of less than 10-20 BNLH per sweep set), there is no need to treat again. Keep a record of the BNLH numbers and check those same beds again the following year to see if the numbers have increased.
7. In most cases, there is no need to apply broad-spectrum insecticides (organophosphates, carbamates, pyrethroids) to control BNLH for two or more consecutive years. These insecticides will disrupt the biological control of other pests such as Sparganothis fruitworm and therefore cause increases in insecticide use.
8. If treatment is necessary, we have a few options to manage BNLH. The best timing for insecticide treatment is before bloom to target the young nymphs, i.e., at this time of the year. We recommend the use of organophosphates such as Diazinon (diazinon) and Orthene (acephate), carbamates like Sevin (carbaryl), and pyrethroids like Fanfare (bifenthrin) and Danitol (fenpropathrin). Although not proven scientifically, there are claims that Orthene and Sevin can reduce pollinator activity by repelling bees. The neonicotinoids Assail (acetamiprid) and Actara (thiamethoxam) also work well against nymphs, but we do not recommend the use of neonicotinoids before bloom due to potential negative effects on bees; neonicotinoids are systemic insecticides that can accumulate in the pollen and nectar. Closer (sulfoxaflor) is a new registered insecticide in cranberries with a similar mode of action as the neonicotinoids but that belongs to a different class of insecticides. We have tested Closer in small plot trials at the P.E. Marucci Center and shown that it is effective against BNLH nymphs; however, more data are needed to confirm its efficacy at larger scales in commercial farms.