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Peach IPM Report - Week 3/25 & 4/1

Western Flower Thrip Larva
This week's report includes:
✔ Petal Fall Insect Complex
✔ Oriental Fruit Moth (OFM)
✔ Green Peach Aphids (GPA)
✔ Thrips
✔ Bacterial Spot
✔ Rusty Spot
✔ Brown Rot
✔ Peach Scab

Dean Polk, Fruit IPM Agent and
David Schmitt, Eugene Rizio and Atanas Atanassov,
Program Associates, Tree Fruit IPM

✔ Petal Fall Insect Complex (From the Week of 3/25):
An OFM biofix was set at the Rutgers Research Farm in Centerton on 3/21. OFM were captured at sustained rates in commercial orchards a few days later. Treatments for the first flight will be due at 170-200 degree days after first catch or “biofix.” This timing usually coincides with late petal fall to shuck split. Current forecasts indicate this will be on or about 4/6 to 4/10 in Gloucester and other southern counties.

While organophosphates (Imidan, Diazinon), carbamates (Lannate, Sevin), and synthetic pyrethroids (Asana, Ambush/Pounce, Warrior, Baythroid) are rated for control of petal fall insect pests, experience has shown that the pyrethroids may be weak at lower rates against plum curculio (PC). If using any pyrethroids (Ambush, Asana, Baythroid, Danitol, Perm-Up, Pounce, Warrior, Lambda-Cy, or any of the other generics), use a high rate in order to control both OFM and PC. Endigo, a premix for stone fruit; contains the active ingredients for warrior and actara and is a good choice around shuck split for the entire insect complex. Rotate pyrethroids (IRAC group 3) and O.P.’s (IRAC group 1B) with different chemistries for resistance management (see IRAC groups below).

The 3 primary arthropod targets at petal fall are OFM, PC and various catfacing insects, primarily tarnished plant bug and stinkbugs.

✔ Oriental Fruit Moth (OFM) (Week of 4/1):
With the cooler weather has come a slowing in insect development. About 7-10 days ago it looked like OFM egg laying and hatch would be well under way by the first week of April. Now we are looking at 4/10 to 13 as the ideal dates to spray. Treatments should be applied between 170 to 200 degree days base 45 after the first sustained catch (Biofix). We are currently at 122DD in southern counties. Skybit predictions are to reach 173 DD in southern counties by 4/10. Ideally this will be applied in a full cover application, alternate middle sprays applied just a few days apart will also work. A second insecticide cover should be applied between 350-375 DD. This is predicted to be on or about 4/30 to 5/2 in southern counties. Note that many blocks may still have considerable bloom. Since the biofix was set using a very high population at RAREC, and trap captures in commercial orchards are near zero, most growers should have no problem delaying the petal fall spray until all petals are off the tree. Do not apply insecticides during bloom.

If using Imidan for OFM control, do not use less than 3#/ac. If the temperatures warm up, we could see increased plum curculio and catfacing insect activity. See above (week of 3/25) and the NJ Commercial tree Fruit Production guide for insecticide options.

The first and second spray dates for southern counties are as follows:

County / Region
1st Spray Date
2nd Spray Date
Gloucester – Southern
Monmouth – Central
Hunterdon – Northern

✔ Green Peach Aphids (GPA):
At this time of year, growers should not tolerate more than 2 colonies per tree on peach or 1 colony per tree on nectarines. While this is a very conservative estimate for peaches, aphid populations should definitely not be tolerated on nectarines, since they will directly damage and deform the fruit. Aphids should not be an issue where Esteem was applied at the delayed dormant stage.

The neonicotinoids (Actara, Assail, Provado/ Admire) and the premixes, Voliam Flexi and Leverage are the best materials to control aphids. Some of these have a wider spectrum of control than others. For example, Admire has only aphid activity at this time of year. Actara will control plum curculio, tarnished plant bug, and stink bugs (at a higher rate of 4.5 to 5.5 oz/A as opposed to 3-4 oz/A for aphids). Assail will control aphids, OFM, plant bugs and native stink bugs at the higher rate. Leverage (a premix of Admire + Baythroid), and Voliam Flexi (a premix of Actara + Altacor) are rated excellent for aphid control. Endigo ( a premix of Actara + Warrior) should work well also. See the Tree Fruit Production Guide for further details. Lannate and Thionex will also suppress aphids, but not as effectively as the neonicotinoids. This is the last year for Thionex in peaches and nectarines, and this material is better left for early brown marmorated stink bug (BMSB) control if needed later, but still “early season”.

Fig 1: Western Flower Thrip larva
✔ Thrips (From the Week of 3/25):
Thrips overwinter as adults in leaf litter and other protected places. Flower thrips and western flower thrips can start moving into orchards sometime during the bloom to petal fall period and can be troublesome on nectarines in some years. While it is impossible to predict insect activity over the long term, we have had a very mild winter and relatively dry conditions. This may favor thrips survival and lead to higher populations than normal. Make sure to check your flowers and early developing fruit.

Lannate, and Delegate are effective for thrips control at petal fall to shuck split. Carzol may be used up to petal fall. Entrust can be purchased if you want the slightly more active ingredient that was in Spintor. Actara can provide suppression. Thrips monitoring can be accomplished by collecting a sample of blossoms; opening the shucks and examining the inside with a hand lens. See fig. 1. If thrips are present inside the shucks, treatment with an effective insecticide is suggested. As of 4/3 thrips activity has not been observed in nectarine flowers, however if temperatures climb into the 80’s thrips could become active. Although early thrips injury is sometimes seen on both peaches and nectarines at harvest, they are generally considered more damaging to nectarines.

✔ Bacterial Spot:
Treatments using copper formulations or terramycin should start at petal fall. Oxytetracyline (a specific type of terramycin – Mycoshield and FireLine) formulations have limited residual activity, and are thought to have as much as 24 hours “back-action”. Mycoshield/FireLine works best when applied as dilute as possible and under slow drying conditions up to 4 days prior to a rain event. Bacterial spot could be an issue this season if our current windy weather pattern continues. Fruit will be very susceptible at shuck split.

See the production guide for recommended materials and rates. Coppers (Champ, Copper-Count-N, Cuprofix, Kocide, and Nu-Cop) can also be started at late petal to shuck split. Watch your rates, since these can all be phytotoxic, and ironically the same conditions (cooler weather with slow drying conditions) that make antibiotics more effective because of increased uptake, also provide better conditions for more phytotoxicity.

✔ Rusty Spot: Rally should be included at petal fall on rusty spot sensitive varieties. Apply at 2.5 – 5 ozs./acre. Gem alone should be adequate for all diseases, including Rusty Spot when applied at higher rates.

✔ Brown Rot (From the Week of 3/25):
Trees in southern counties are entering petal fall, but much bloom is present in southern, central and northern counties. Blossom infections from the brown rot fungus can occur whenever pistils are exposed and favorable conditions exist. Infections can occur during any wetting period when temperatures are between 41 and 86 ° F, with optimum conditions occurring with wetting and temperatures in the mid 70’s.

If we have prolonged wetting periods, growers are advised to maintain cover sprays as outlined in Norm Lalancette’s article in an earlier newsletter. A key paragraph about control options is reprinted here:
“The recommended fungicides for blossom blight applications consist of the protectants Captan or chlorothalonil (Bravo, Echo, etc.), the site-specific fungicides Vangard or Rovral, or some combination of these two fungicide types. Topsin-M or Topsin- M + Captan could also be used for one of the applications. If peach scab and/or rusty spot are problematic in a block, then Gem or Abound at the highest label rate should be used for the petal fall spray; these materials will control all three diseases at this timing. As a fungicide resistance management strategy, it is highly recommended that DMIs not be used during bloom, but be “saved” for preharvest brown rot control. The DMIs, belonging to FRAC group 3, are listed in Table 6.4 on p. 88 of the 2012 NJ Commercial Tree Fruit Production Guide.”

✔ Peach Scab (From the Week of 3/25):
Scab has become more prevalent and widespread in recent years. As petal fall becomes shuck split, scab becomes an important disease to control. In blocks that had scab last season, increased levels of overwintered scab inoculum are present on last year’s wood, and as rain occurs, spores are splashed onto the fruit during rainy periods from shuck split through the following six weeks. The lesions appear from 40 to 70 days after infection. They first appear as small (1-2 mm) green spots, but enlarge to 2-3 mm and become black as spores are produced. Most lesions are found on the shoulders of the fruit where spores were splashed down from the twig. They do not appear until about redhaven season, but by then the damage has already occurred.
Since conidia begin forming around petal fall, the first scab sprays should begin then. Gem, Bravo, Adament, Pristine, or a Captan/Topsin-M combination are all very effective scab fungicides. These materials are also very effective for blossom blight control. Adament (a premix of trifloxystrobin (Gem) and a very low rate of tebuconazole (Elite)), Gem, and Topsin should be applied at full rates during petal fall to get suppression of lesions. Solid applications are preferable.

Commercial Tree Fruit Recommendations Guide