Cicadas Are Here and Fruit IPM for 5/26/21

Cicadas are Here, There and Everywhere (Depending where you are): 17 year cicadas began emergence last week. These insects while a marvel in the insect world, are also capable of doing considerable damage to young fruit trees, grape vines, and blueberry bushes. After mating they begin to deposit their eggs in slits along small diameter branches. Thin branches which are loaded with fruit weight and damaged by egg laying can break. Some growers have asked about damage and what they can do to prevent it. Most egg laying is starting this week.

As background to consider controls, we need to remember that after these insects spend their nymphal stage underground, feeding on tree roots, they emerge en masse, virtually all at once. While there may be some stragglers, most of the emergence happens in the first few days. After the first week to 10 days no new adults can be found. The last instar nymphs crawl up a vertical surface (commonly a tree). Shortly thereafter, the adult matures and splits out of the nymph exoskeleton, leaving the cast skin or exuvia hanging from the tree. The adult is first a soft light creamy color. As the adult hangs on the tree, it expands its body and the exoskeleton becomes ‘tanned’  or hardened and darker. Only after this process, can they fly and look like the ‘normal’ cicada adult seen in most photos. The adults will mate and lay eggs, and be present for an additional 3-4 weeks. Since the insects are already completely emerged, there is no population increase during this period. Rather, the adults start to die off after mating and egg laying, and by the end of June to early July, the population is gone. We know very little about adult movement and dispersal during those few weeks. We do know that just because a tree or an area of an orchard has many exuvia hanging from the branches, that DOES NOT equate to high numbers of adults in the same area. Most adults will have moved on or have been eaten by a multitude of predators. However, if there are many adults per tree, then damage may occur, and growers may wish to treat the population. Because the adults are constantly moving it is important that whatever insecticide that is used have both initial ‘knockdown’ properties as well as residual properties to kill and/or repel incoming adults.

Moribund cicada adult next to an emergence hole after Imidan treatment.

Cicada exuvia and adults on apple.

Dr. Chris Bergh did some work with Brood X in Winchester, VA during 2004. (Bergh, J.C. and Engelman, J.P. 2005. Arthropod Management Tests). Measurements included the number of oviposition slits per branch, the number of flagged shoots per tree and the number of fallen shoots per tree. That data is reprinted below. By the end of the ‘cicada season’ (mid June), Lannate, Asana, Danitol and Warrior showed significantly less egg laying than the untreated controls. Also by the end of the season (June 24), the trees that had been treated with Asana and Danitol had fewer flagged shoots, and only those that had been treated with Danitol had no fallen shoots. There were no statistical differences between any of the treatments and the check with regards to the number of fallen shoots per tree. Note that Calypso is no longer labeled or available.

Other insecticides may give some initial knock-down, but lack residual properties. One farm was seen this week where Imidan had been applied, but only 1 semi-dead adult (moribund) adult was seen. While the trees were littered with exuvia, and there were many emergence holes, there were no dead adults on the ground. This is a large insect, and like BMSB it can recover from some insecticides, at first being knocked down, then later recovering. Therefore, Imidan would not be an insecticide to use for controlling this insect.

Other work in the mid-Atlantic area has shown that Assail to be one of the most effective neonicotinoid materials for killing adults (Biddinger and Hull, 2004). Hogmire and Winfield (2004) showed that of the materials tested, Danitol was the most effective at preventing oviposition scars, but Assail, Warrior and Asana were also effective in preventing damage. In general neonicotinoid materials may last longer than pyrethroids, but they are systemic and may be in the leaf and not on the surface, so after a few days the adults (which don’t really feed) may not get a toxic exposure. In addition the pyrethroids have repellency properties, so part of their activity may be to both kill the adults and repel other adults from a treated area.

The bottom line – If you see the adults (and not just hear them) and have heavy adult populations, and wish to treat to prevent wood breakage from egg laying, then choose a material with demonstrated effectiveness that includes Assail, Danitol, Asana, Warrior, other pyrethroids, and possibly Lannate.

Peach:

Oriental Fruit Moth: We are between 1^st and 2^nd generations at the present time. Growers that have utilized mating disruption for OFM should continue to focus on PC; GPA; and catfacing insect pests as described below. Second generation timings will be in about two weeks in southern counties. Overall the adult population is low, but above the treatment threshold of 8 moths per trap on some farms in northern counties.

Plum Curculio (PC): PC activity usually peaks about mid-May and may linger into early June. Fresh egg scars continue to be seen, particularly in northern county orchards. Preferred materials that offer PC control now are Avaunt, and Imidan. If using high rates of a neonicotinoid (i.e. Actara, Belay, Assail), be aware that there is a synergistic effect when used in tank mixes with DMI materials (i.e. Rally) with regard to bee toxicity. Neonicotinoids should not be used if there are any flowering weeds in your orchard. Those flowering weeds will attract bees, which will be killed by the insecticide. The use of most of these products when bees are present is off label and therefore not legal. If pyrethroids are being used, then high rates are advisable, since low rates often do not control PC, especially in hot weather. Where PC is a problem, growers should rotate away from pyrethroid insecticides if possible. Actara and Belay will also control PC (and GPA), but not OFM. Fresh injury and activity was seen this week in both southern and northern counties.

Green Peach Aphids (GPA): Scouting has shown that GPA is not a problem in most orchards. If aphids are at treatment level, and your ground cover is clean of blooming weeds, a good choice that will cover catfacing insects, aphids, and plum curculio is Thiamethoxam (Actara and in VoliamFlexi). Actara will not control OFM. Examine trees for the presence of colonies by standing back and looking at the entire tree. Clusters of curled leaves will define a single colony. Count the number of colonies on ten trees and use a treatment threshold of 2 colonies/tree at petal fall to shuck split for peach, and 1 colony/tree for nectarine. If treating aphids alone then Movento @ 6 oz/A is a good non-neonicotinoid choice. Movento must be combined with a spreader/penetrant spray adjuvant. Used later during late May to early June this will also control scale. Movento will not control PC or catfacing insects. Additional choices include Closer (also effective for scale), Belay and others. See the 2021-22 Tree Fruit Production Guide pp168-169 for a complete list. Lannate can also be used, but is not quite as effective and is a weak PC material.

Tarnished Plant Bugs and Other Catfacing Insects:  This is the other key insect complex at this time of year. Stink bugs have been found at low levels in beating tray samples. Tarnished plant bugs will become more of an issue as temperatures warm and mowing and other ground cover activities become more common. General spray timing at this time of year should still be targeted for Oriental Fruit Moth and/or Plum Curculio (PC). Most OFM materials, except Altacor and Exirel, will have some efficacy for plant bugs.

Scale Insects: White peach scale (WPS) crawlers are very close to emergence in southern counties. San Jose scale (SJS) crawlers usually begin emergence about a week or ten days later, usually late May/Early June. If you have scale infestations on your trees, it is important to note if crawlers are present, even if you treated with oil in the early spring. If crawlers are present then treatment options include Esteem, Movento, Centaur, Venerate, and Diazinon. Esteem, Centaur, Venerate and Movento should be applied at the beginning of crawler emergence. Venerate needs to be applied at the low rate of 1 qt/A. Diazinon is labeled for only one post bloom or foliar application on stone fruit (Rec = max. of 2 lb/acre of the 50W). The apple label allows up to 2 foliar applications per year as long as a prebloom application was not made. The peach label allows 1 foliar application per year. Foliar applications may cause russet on apples, but has worked in the field for scale crawlers as long as applications are made 1-2 weeks after the start of crawler emergence and again 2 weeks later. Belay and Assail are also effective against scale crawlers but may need more than one application during the emergence which typically lasts about 4 weeks for WPS and 6 weeks for SJS.

Lesser Peach Tree Borer and Peach Tree Borer: Lesser Borer adults began flying last week in southern counties. If you haven’t placed mating disruption dispensers yet there is still time to get them out before the greater peach tree borer flight which usually begins in June.

Bacterial Spot: Maintain tight covers with antibiotics until pit hardening. Typical antibiotics used include various copper and oxytetracycline formulations. Full covers with at least 100 gpa are recommended around wetting periods or severe weather. No bacterial spot cankers or leaf symptoms have been observed in southern county orchards as of yet.

Peach Scab: In addition to Rusty Spot and Bacterial Spot, peach scab requires protective applications starting at petal fall. Peach scab cankers begin to expand at bloom and by shuck split begin to shed spores during wetting periods. Topsin, Topsin/Captan combinations, Flint Extra, Inspire Super, and especially Quadris Top applied at petal fall are the best materials for blocks that had scab last year. Quadris Top, Flint Extra and Topsin should be used at the high rate to suppress overwintering lesions on the wood. Quadris Top contains azoxystrobin which is phytotoxic to many apple varieties. Phytotoxic residues can remain in the tank for long periods after an application is made, even if a tank cleaner is used. Do not use Quadris Top or Abound in the same sprayer used for apples. Bravo (chlorothalonil) is also a good protectant that may be applied no later than shuck split. Captan is also helpful in cover sprays after shuck split where scab was troublesome last year. Maintain effective scab materials in cover sprays through June.

Rusty Spot: Rusty spot symptoms began to appear last week in southern counties and infections are ongoing until pit hardening. If you are using Flint Extra, Inspire Super, or Quadris Top for scab, these materials will also control rusty spot. After petal fall, maintain coverage with effective materials such as Rally, Rhyme, or potassium bicarbonate products.

Apple:

Codling Moth (CM): Biofixes for Codling moth have been set. See the chart below. Timings for codling moth treatments by chemistry are listed below.

Tufted Apple Budmoth (TABM): A biofix was set statewide on May 3. The first alternate middle applications for TABM will be on or about May 28 in all counties. This has been considered a minor pest in recent years. With the exception of Assail and other sucking insect materials, and granulosis virus formulations (e.g. Madex), most materials used for Codling Moth will control TABM.

Diseases: Powdery Mildew, Cedar Apple Rust, and Summer Diseases are diseases of concern at this time. The NEWA scab models calculating about 100% ascospore maturity in all counties. A prolonged wetting period could yield a severe infection period with this many mature spores. Primary apple scab spores are released during any substantial wetting and infection period, and since most ascospores are mature, primary scab season is nearing the end in all counties. Watch the forecast so your orchard can be well covered in the event of a prolonged wetting period. Growers should continue to manage for primary scab through May since microclimates may affect spore maturity and because it has been dry the next significant wetting may still result in a primary scab infection.

Powdery Mildew is a disease we not have been much concerned with in recent years because we have not seen it for so long. This year however  infected shoots were observed in a block of Ginger Golds in Gloucester County. These shoots were infected as they pushed out from buds that were infected last year. The infected shoots will produce inoculum for secondary infections during the summer. Effective materials at this time include Inspire Super, Merivon and Luna Sensation. See the NJ Tree Fruit Production guide for rates and efficacies.

Powdery mildew infection on apple terminal

Cedar apple rust infections can occur anytime between pink and 3^rd cover. Symptoms from early infections began to appear last week in southern counties. Summer diseases such as rots and sooty botch are beginning to overlap with early season diseases. Most scab materials will control summer diseases. Growers who have had trouble with bitter rot may wish to include a phosphonate product (e.g. pro-phyt) with captan. Phosphonates contain potassium and my contribute to bitter pit so avoid the use of phosphonates on Honeycrisp until after cell division is complete, usually sometime after the thinning window has closed.

Grapes:

Diseases: Grape diseases active at this growth stage are phomopsis, powdery mildew and black rot. As we approach bloom botrytis will also be a target. Disease infection periods can be monitored using the NEWA models. Growers should monitor potential Powdery Mildew infection periods as the current weather pattern is very favorable for this disease. Choose the weather station closest to your vineyard.

Insects: Leafhoppers have been seen in a few spots. This complex is generally not of concern. Potato leafhoppers, which arrive sometime in June, can cause some minor damage. Spotted Lantern Fly nymphs are now hatching in southern counties. These nymphs do little damage and generally don’t need special treatments when present. Even so, vineyards should be monitored for SLF presence and if they are found use an insecticide effective for SLF when treating for Grape Berry Moth in late June.

Scouting Calendar Tree Fruit Southern Counties

The following table is intended as an aid for orchard scouting. I t should not be used to time pesticide applications. Median dates for pest events and crop phenology are displayed. These dates are compiled from observations made since 1995 in Gloucester County. Events in northern New Jersey should occur 7-10 days later.

 Tree  Fruit Trap Counts – Southern Counties

Tree  Fruit Trap Counts – Northern Counties

Blueberries:

Leps and Other ‘Worms’: During this past week’s scouting, Lep larvae averaged 0.02 with a high of 0.3 larvae per push.  Most of these were green fruitworm and spanworm.   The average per bush of infested berries was 0.13 with a high of 1.8 berries per bush. We are still finding some gypsy moth both in Atlantic and Burlington county. Overall, a slight increase since last week was seen, and averaged 0.026 per bush with a high of 1.2 larvae per bush. The high number is over threshold and needed to be treated. Therefore, if you have any gypsy moth in your woods that surrounds your fields, take a look and treat if needed.

Plum Curculio: During this past week PC adult activity averaged 0.04 with ahigh of 0.6 per bush. This shows that PD activity in ongoing, and that this insect still has to be targeted in the spray program in some areas, especially around wooded borders We also incorporated fruit counts, which averaged 0.80 with a high of 9.8 infested berries per bush. Most of these should drop before harvest.

Aphids: Developing aphid colonies are easy to find this year. The colonies are small, but fields averages just over 6% of new shoots infested with a high of 36%. We have been working with a provisional treatment threshold of 10% of shoots infested, which we think is a little too high, given the occurrence of scorch virus over the past several years.