Effectively controlling plum curculio in stone and pome fruits

Growers have many options for plum curculio control, but all have different modes of action.

With stone fruits at shuck-split and apples sizing, and the warm temperatures predicted for this week, plum curculio is likely to begin egglaying in fruit. There are many insecticides available for controlling plum curculio, but their performance characteristics vary greatly compared to our traditional broad-spectrum chemistries. These conventional insecticides, such as organophosphates and pyrethroids, work primarily as lethal contact poisons on plum curculio adults in the tree canopy. Avaunt also works primarily by lethal activity, but ingestion is the important means for delivering the poison.

Neonicotinoids are highly lethal to plum curculio via contact for the first several days after application, but as these systemic compounds move into plant tissue, they protect fruit from plum curclio injury via their oviposition (egglaying) deterrence and anti-feedant modes of activity. Neonicotinoids and organophosphates can also be used as rescue treatments because they have a curative action that can kill eggs and larvae that are already present in the fruit.

Voliam flexi can be used for plum curculio control, but only the neonicotinoid (Actara) component will be effective against plum curculio. Also, 4.5 to 5.5 ounces of Actara is the recommended rate for plum curculio control, and Voliam flexi is labeled at 4-7 ounces; be sure to apply an adequate amount of Voliam flexi to meet these recommended rates. Leverage (imidacloprid plus cyfluthrin) and Voliam Xpress (Chlorantraniliprole plus Lamda-cyhalothrin) are other pre-mix materials labeled for plum curculio control. For organic growers, Venerate has been shown to provide good control.

The table below is designed to summarize several key variables that can help growers determine how to optimize the performance of various insecticides for integrated pest management (IPM) programs. Several other compounds, like Exirel, Rimon, Esteem and Delegate, are commonly used in tree fruit pest management programs and have activity on plum curculio worth noting.

Rimon, when targeted to control obliquebanded leafroller or codling moth at petal fall, will effectively sterilize plum curculio eggs when adults are exposed to residues in the tree canopy. These sub-lethal effects will not prevent injury to fruit from adults, but will result in nonviable plum curculio eggs, thus no live larvae. Delegate and Exirel have been shown to provide fair to good activity, but ingestion by plum curculio adults is important for control. Esteem, when used approximately two weeks post-harvest in cherries (San Jose scale crawler timing) will reduce female plum curculio overwintering viability. However, Rimon, Esteem and Delegate are not labeled for stand-alone plum curculio control, but when used in pest management programs may contribute to overall plum curculio population management.

Optimal timing and order selection of insecticides for plum curculio management is based on matching the performance characteristics of each compound with plum curculio life-cycle development (see photo) and tree phenology (see table). Because organophosphates and pyrethroid insecticides are contact poisons, they can be used as early as petal fall to knock beetles out of the tree canopy. However, Michigan State University Extension cautions using pyrethroids as they are toxic to mite predators. Plum curculio adults feed on tree parts during bloom and petal fall, so Avaunt can be used at this petal fall timing.

The performance of neonicotinoids is optimized when sprays are made after fruit set (pome fruits) or shuck-split (stone fruits), so that fruit and foliage are both covered. Surround will not work unless the tree and fruit are completely covered, so multiple sprays are needed on the tree prior to plum curculio oviposition activity. If plum curculio infestation occurs and a rescue treatment is needed, organophosphates and neonicotinoids can provide curative action up to two weeks after plum curculio infestation, although in some cases dead cadavers can still be found in fruit.

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Plum curculio life stage control timing for reduced risk and OP-replacement insecticides.

Insecticidal modes of activity on plum curculio life stages

Compounds2

Chemical class / activity

Crop

Rate

Crop stage and initial control timing (DD50)

Imidan 70W**

Organophosphate

Pome fruit

3 pounds

Petal fall (approx. 250 DD)

Lethal via contact

Stone fruit

2.125 pounds

Petal fall (approx. 175 DD)

Actara 25WG**

Neonicotinoid

Pome fruit

4.5 ounces

Petal fall + 3-5 days (approx. 300 DD)

Lethal, Antifeedant and Curative

Stone fruit

4.5 ounces

Shuck-off (approx. 250 DD)

Assail 30SG**

Neonicotinoid

Pome fruit

6 ounces

Petal fall + 3-5 days (approx. 300 DD)

Lethal, Antifeedant and Curative

Stone fruit

Shuck-off (approx. 250 DD)

Belay 2.13SC**

Neonicotinoid

Pome fruit

6 ounces

Petal fall + 3-5 days (approx. 300 DD)

Lethal, Antifeedant and Curative

Peach

Shuck-off (approx. 250 DD)

Exirel 10SE

Diamide

Pome fruit

6 ounces

Petal fall (approx. 250 DD)

Lethal via ingestion

Stone fruit

Petal fall (approx. 175 DD)

Delegate 25WG*

Spinosyn

Pome fruit

6 ounces

Petal fall (approx. 250 DD)

Lethal via ingestion

Stone fruit1

Petal fall (approx. 175 DD)

Avaunt 30WG

Oxadiazine

Pome fruit

5 ounces

Petal fall (approx. 250 DD)

Lethal via ingestion

Stone fruit

Petal fall (approx. 175 DD)

Venerate XC

Biopesticide

Pome & stone fruits

4-8 quarts

Petal fall (approx. 250 DD)

Pyrethroids

Asana, Warrior, Baythroid

Pome fruit Stone fruit

Variable

Petal fall (approx. 250 DD)

Lethal, repellent

Petal fall (approx. 175 DD)

Rimon* (targeting codling moth, obliquebanded leafroller)

IGR

Pome fruit

20-40 ounces

Petal fall (approx. 250 DD)

Egg sterilization

Stone fruit

Esteem* (targeting scale)

IGR

Pome fruit

5 ounces

Post-harvest

Adult sterilization

Stone fruit

Leverage 2.7F

Pyrethroid + Neonicitinoid

Pome fruit

4.4-5.1 ounces

Petal fall (approx. 250 DD)

Lethal, Repellent, Curative

Stone fruit

4.5-5.1 ounces

Shuck-off (approx. 250 DD)

Voliam Xpress

Pyrethroid + Diamide

Pome fruit

6-12 ounces

Petal fall (approx. 250 DD)

Lethal, Repellent

Stone fruit

6-12 ounces

Petal fall (approx. 175 DD)

Voliam flexi

Neonicotinoid + Diamide

Pome fruit

6-7 ounces

Petal fall (approx. 250 DD)

Lethal, Antifeedant, Curative

Stone fruit

6-7 ounces

Shuck-off (approx. 250 DD)

*Not labeled for plum curculio (or just for PC suppression)
**Have curative properties that can kill eggs and larvae that are already present in the fruit.
Modified from John Wise, Nikki Rothwell, David Epstein, Larry Gut, and Mark Whalon, 2009.

Drs. Wise and Rothwell’s work is funded in part by MSU‘s AgBioResearch.

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