Plum curculio management in stone and pome fruits

John Wise, Michigan State University Extension, Department of Entomology, Nikki Rothwell<rothwel3@msu.edu>, Michigan State University Extension, and Mark Whalon, Michigan State University Extension, Department of Entomology - May 21, 2013

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

Plum curculio is a key early season pest on pome and stone fruits. There are many insecticides (and an organic option) available for control of plum curculio, but according to Michigan State University Extension, their performance characteristics vary greatly compared to our traditional broad-spectrum chemistries. These conventional insecticides, such as organophosphates (OP) 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 OP’s 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, growers should remember that 4.5 to 5.5 ounces of Actara is the recommended rate for plum curculio control, and Voliam flexi is labeled at 4 to 7 ounces; growers should be sure to apply an adequate amount of Voliam flexi to meet these recommended rates. Leverage (imidacloprid + cyfluthrin) and Voliam Xpress (Chlorantraniliprole + Lamda-cyhalothrin) are other pre-mix materials labeled for plum curculio control.

For organic growers, Surround WP can reduce plum curculio injury to fruit if applied to attain a heavy coating on the tree canopy; this kaolin clay product works as a plum curculio repellent. Building up and maintaining several coats of the clay on fruit as the fruit continues to grow is key to successful use of this product.

The following table 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 Rimon, Esteem and Delegate, are commonly used in tree fruit pest management programs and have limited activity on plum curculio worth noting. Rimon, when targeted to control obliquebanded leafrollers 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, when ingested by plum curculio adults, will cause moderate levels of mortality. 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.

Control materials for plum curculio

Compounds²	Chemical class / activity	Crop	Rate	Crop stage and initial control timing (DD₅₀)
Guthion 50W**	Organophosphate	Pome fruit	2 lb	Petal fall (approx. 250 DD)
Guthion 50W**	Lethal via contact	Cherries	2 lb	Petal fall (approx. 175 DD)
Imidan 70W**	Organophosphate	Pome fruit	3 lb	Petal fall (approx. 250 DD)
Imidan 70W**	Lethal via contact	Stone fruit	2½ lb	Petal fall (approx. 175 DD)
Actara 25WG**	Neonicotinoid	Pome fruit	4½ oz	Petal fall + 3-5 days (approx. 300 DD)
Actara 25WG**	Lethal, Antifeedant and Curative	Stone fruit	4½ oz	Shuck-off (approx. 250 DD)
Calypso 480SC**	Neonicotinoid	Pome fruit	4 oz	Petal fall + 3-5 days (approx. 300 DD)
Calypso 480SC**	Lethal, Antifeedant and Curative	Stone fruit	4 oz	Shuck-off (approx. 250 DD)
Assail 30SG**	Neonicotinoid	Pome fruit	6 oz	Petal fall + 3-5 days (approx. 300 DD)
Assail 30SG**	Lethal, Antifeedant and Curative	Stone fruit	6 oz	Shuck-off (approx. 250 DD)
Belay 2.13SC**	Neonicotinoid	Pome fruit	6 oz	Petal fall + 3-5 days (approx. 300 DD)
Belay 2.13SC**	Lethal, Antifeedant and Curative	Peach	6 oz	Shuck-off (approx. 250 DD)
Delegate 25WG*	Spinosyn	Pome fruit ¹	6 oz	Petal fall (approx. 250 DD)
Delegate 25WG*	Lethal via ingestion	Stone fruit ¹	6 oz	Petal fall (approx. 175 DD)
Avaunt 30WG	Oxadiazine	Pome fruit ¹	5 oz	Petal fall (approx. 250 DD)
Avaunt 30WG	Lethal via ingestion	Stone fruit ¹	5 oz	Petal fall (approx. 175 DD)
Surround WP	Particle film Repellent	Pome & Stone Fruits	Usually 16 lb by First Cover	Multiple applications starting before bloom to achieve complete coverage
Pyrethroids	Asana, Warrior, Baythroid	Pome fruit	Variable	Petal fall (approx. 250 DD)
Pyrethroids	Lethal, repellent	Stone fruit	Variable	Petal fall (approx. 175 DD)
Rimon* (targeting codling moth, OBLR)	IGR	Pome fruit	20-40 oz	Petal fall (approx. 250 DD)
Rimon* (targeting codling moth, OBLR)	Egg sterilization	Stone fruit	20-40 oz	Petal fall (approx. 250 DD)
Esteem* (targeting scale)	IGR	Pome fruit	5 oz	Post-harvest
Esteem* (targeting scale)	Adult sterilization	Stone fruit	5 oz	Post-harvest
Leverage 2.7F	Pyrethroid + Neonicitinoid	Pome fruit	4.4-5.1 oz	Petal fall (approx. 250 DD)
Leverage 2.7F	Lethal, Repellent, Curative	Stone fruit	4.5-5.1 oz	Shuck-off (approx. 250 DD)
Voliam Xpress	Pyrethroid + Diamide	Pome fruit	6-12 oz	Petal fall (approx. 250 DD)
Voliam Xpress	Lethal, Repellent	Stone fruit	6-12 oz	Petal fall (approx. 175 DD)
Voliam flexi	Neonicotinoid + Diamide	Pome fruit	6-7 oz	Petal fall (approx. 250 DD)
Voliam flexi	Lethal, Antifeedant, Curative	Stone fruit	6-7 oz	Shuck-off (approx. 250 DD)

*Not labeled for plum curculio (or just for plum curculio 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.

Optimal timing and order selection of insecticides for plum curculio management is based on matching the performance characteristics of each chemistry with plum curculio lifecycle development and tree phenology. 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, we do caution the use of 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.

Dr. Wise's work is funded in part by MSU's AgBioResearch.

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