Tree Fruit IPM Report: week ending 4/13/2013

• Peach
• Apple
• Pear
• Scouting Calendar
• Trap Counts (Southern Counties)

Peach

Petal Fall Insect Complex: An OFM biofix has not yet been set in southern counties, but should be by the end of this week. 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. 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), especially in hot weather. 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 native stinkbugs.

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 will also suppress aphids, but not as effectively as the neonicotinoids.

Thrips:  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. If thrips are present inside the shucks, treatment with an effective insecticide is suggested. 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 again 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 bloom to petal fall. 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. Avoid Captan/copper tank mixes if: it is very hot; has been overcast for several days in arow; or if applying at low volume. Do not acidify spray solutions when using copper.

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: Some trees in southern counties are entering petal fall, but there is still much bloom 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 with effective protectants.

Peach Scab: 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.  In orchards that had scab last year, Make a solid application of  Gem or Topsin at full rates during petal fall to get suppression of lesions. Solid applications are preferable.

Apple

Diseases: Apple Scab, Powdery Mildew, Cedar Apple Rust, are diseases of concern at this time. Primary apple scab spores are being released during any substantial wetting and infection period. Make sure you are well covered.Cedar apple rust infections can occur anytime between pink and 3^rd cover. The DMI fungicides Rally, Procure, and Indar are standard scab, rust, and mildew materials. These materials and should be combined with a protectant, usually an EBDC such as Manzate. However new materials available this year allow us formulate new strategies to manage primary scab without relying solely on DMI’s.  Cedar apple rust galls expanded during the last rain so inoculum for that disease will be available from now until about 1st cover.

Pear

Pear Psylla: Pear Psylla nymphs began hatching early this week. Nymphs will feed on developing clusters through bloom. The best option for control at popcorn is Surround @ 25-50#/ac.

Fire Blight: From a calendar perspective, blossom sprays using Streptomycin should be applied on a 3-7 day schedule or anytime temperatures are 65° F or above and the relative humidity is 60% or above. Mycoshield now has a supplemental label allowing use on apples. Rotations of Streptomycin and Oxytetracyclene will help manage resistance. However, from a more accurate and economical modeling perspective, using the NEWA site, There is a risk of fireblight for the end of the week in South Harrison Twp. (Gloucester County) if pears have blossoms open.

Scouting Calendar

The following table is intended as an aid for orchard scouting. It 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.

Trap Counts – Southern Counties