nenuphar (Herbst) in Peach
I. Introduction: The plum curculio (PC)
under the apple
section, but injury and monitoring are somewhat different with
II. Injury: Adults first feed on
buds, flowers, shucks, and setting fruit. Adults will often feed
developing shuck (left photo below) and young peach during the
petal fall periods. Egg-laying scars are the most common injury
be most easily found on fruit from outside rows near
Larvae (right photo below) tunnel into developing fruit and feed
pit. First brood larval injury will cause fruit drop. Second
will usually not cause drop, but will provide a wounded fruit
brown rot and other diseases to develop.
III. Monitoring: Monitoring of PC
concentrated from bloom through two weeks after shuck-fall.
can be done with a beating tray by holding a large square yard
the tree and beating on a branch three times with a rubber
stick. Fruit should also be examined by counting a minimum of
per block for egg-laying scars or feeding injury. Early control
overwintering generation is critical so that egg laying is
Additional monitoring for the second adult PC
should be done during July. Monitoring can be done with a
by holding a large square yard cloth beneath the tree and
beating on a
branch three times with a rubber mallet or rubber-wrapped stick.
should also be examined by counting a minimum of 200 fruit per
egg-laying scars or feeding injury.
No economic threshold levels have been
However since PC is a direct pest, no more than 1/2 to 1 percent
injury should be tolerated.
(A note on plum curculio strains. There are
strains of plum curculio. The northern strain has an obligatory
requirement. Therefore there is a single generation per season.
strain lacks this chilling requirement and can develop two
seasonally. A rough
map showing the distribution of the northern
(double-brooded) strains was developed by Chapman (1938).
are genetic differences among geographic strains of PC (Zhang et
2008). Furthermore, there are Wolbachia
symbionts in PC, also with geographical differences in
genetics (Zhang et al. 2010). These differences in Wobachia infections likely
in observed differences to mate within and among PC strains (Zhang
Pfeiffer. 2010. Analysis
associated with Conotrachelus
Curculionidae) in the eastern United
States. Environ. Entomol. 39: 396-405.
X., J. Tu, S. Luckhart and D. G. Pfeiffer. 2008. Genetic
diversity of plum curculio, Conotrachelus
nenuphar (Herbst) (Coleoptera: Curculionidae) among
geographical populations in the eastern United States.
Ann. Entomol. Soc. Am. 101: 824-832.
Pfeiffer. 2008. Evaluation
of reproductive compatibility of interstrain matings
among plum curculio populations in the eastern United
States. Environ. Entomol.
This is taken primarily from a chapter by D.
Polk, H. W. Hogmire
and C. M. Felland on peach direct pests, reprinted with permission
Orchard Monitoring Guide, published by NRAES, 152 Riley-Robb
Ithaca, New York 14853-5701. (607) 255-7654.
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