How to Manage Pests
UC Pest Management Guidelines
False Chinch Bug
Scientific name: Nysius raphanus
(Reviewed 10/13, updated 10/13)
In this Guideline:
Description of the pests
False chinch bug is an occasional pest of young pomegranate. The adult is gray to light brown, elongate, and about 0.12 inch (3 mm) long. Females lay eggs on host plants or in cracks in the soil. The pale gray nymphs have reddish brown abdomens. There are four to seven generations per year, with all stages present throughout the year.
False chinch bug nymphs spend the winter on weeds. During early spring, bugs primarily feed on foliage, stems, and seeds of cruciferous weeds. Important weeds that serve as hosts include wild mustard, wild radish, shepherd's-purse, and London rocket. When vegetation dries or is cut, bugs move to feed on virtually any nearby green plants, including irrigated fruit and nut trees, grains, and vegetable crops. The most serious infestations result from spring migrations; however, fall migrations can also occur. Adult bugs may swarm around trees in a manner superficially resembling leafhoppers.
Feeding damage is most severe in the spring as the trees start to leaf. Damage occurs when nymphs migrate from drying weeds or after mowing or plowing weeds. Migration may occur at any time for several days from April to October, but are most common in May through July. Chinch bugs do not stay in one spot for very long and can spread out over an orchard within a week.
Large numbers of nymphs will stream over the dirt looking for any green vegetation. Heavy nymph infestations can kill sucker shoots in less than a day. This damage can occur within hours because the nymphs apparently inject a toxin while feeding. The leaves dry up and are covered with fecal spots. Usually the nymphs do not climb higher than 1 to 2 feet on trees, so they pose little risk to mature trees. Young trees 1 to 2 years old may suffer severe damage.
Control weeds, especially in the first two years after planting pomegranates. Reducing bug numbers in weeds and neighboring agricultural fields prevents migration into orchards. Where possible manage weedy areas such as ditches, pastures, and grasslands adjacent to orchards to prevent migration from these areas into pomegranate orchards. If heavy infestations of nymphs threaten young trees, treat immediately.
Disc under shepherd's-purse, London rocket stands, and other host weeds about 3 weeks before budbreak in young pomegranate trees. Waiting to disc after budbreak may result in heavy movement of bugs from the weeds to the trees.
In the past and in other crops, a barrier of water has been used to prevent ground dwelling beetles from entering orchards. Creating a ditch filled with water between the migrating bugs and the orchard may prevent movement into the orchard and subsequent damage.
Organically Acceptable Methods
Cultural control methods and applications of rosemary oil plus peppermint oil (Ecotrol) or pyrethrin may be effective.
Monitoring and Treatment Decisions
Visually inspect or use a sweep net to monitor weeds in fields or borders near young pomegranates for developing populations. False chinch bugs often hide under weeds at the soil line during the day. Visually inspect weeds by pulling them out of the ground, exposing the bugs to light. The false chinch bugs will begin to move around, making them easier to spot. In addition to weeds, inspect growth tubes or cartons used to protect young trees for false chinch bugs hiding inside. Be aware that populations will be moving around so you may need to monitor the entire orchard.
If possible, manage false chinch bugs in weeds in and adjacent to the orchard before migrations occur using cultural control methods or pesticides. Pay special attention when weeds are drying or after mowing or disking. Treat for chinch bug in neighboring crops according to that crop's Pest Management Guidelines, to prevent migration into pomegranate. When nymphs are migrating into orchards, spraying them on the ground may be enough to prevent damage.
If treatment of young trees becomes necessary, methomyl (Lannate) is the most effective registered material. However, methomyl disrupts natural enemies needed for other pests. The softer insecticides such as rosemary oil and peppermint oil (Ecotrol) and organic pyrethrin (PyGanic) have a very short residual and are less efficacious than methomyl.
UC IPM Pest Management Guidelines:
Insects and mites
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insects and Mites:E. E. Grafton-Cardwell, Entomology, UC Riverside and Kearney Agricultural Center, Parlier