Leafrollers on Ornamental and Fruit Trees

Integrated Pest Management for Home Gardeners and Landscape Professionals

Leafrollers, the larvae of certain tortri- cid moths, often feed and pupate with- in the protection of rolled-up leaves. Several species can cause problems on fruit and ornamental trees in Cali- fornia. The fruittree leafroller, Archips argyrospila, is the most common lea- froller pest in landscapes throughout the state. It occurs on many ornamental trees—including ash, birch, California Figure 3. Fruittree leafroller larva feed- buckeye, box elder, elm, locust, maple, ing inside a leaf it has rolled, or webbed, poplar, rose, and willow—and is par- together. ticularly damaging to deciduous and live oaks. It also attacks numerous fruit and nut trees including almond, apple, apricot, caneberries, cherry, citrus, pear, plum, prune, quince, and walnut. Figure 1. Unhatched (top) and hatched (at bottom with holes) fruittree leafroller eggs. Other leafrollers include the obliqueband- ed leafroller, Choristoneura rosaceana, and the omnivorous leafroller, Platynota stul- tana, which are serious problems on fruit trees. The orange tortrix, Argyrotaenia franciscana, and apple pandemis, Pandemis pyrusana, are pests that occur through- out the year primarily on fruit trees and vines in coastal areas of California.

A new invader, the light brown apple Figure 2. Omnivorous leafroller eggs. moth (LBAM), Epiphyas postvittana, re- Figure 4. Fruittree leafroller larva de- scending on its silken thread. cently has invaded the northern coastal smaller branches. At first a dark gray areas of the state, and high populations or brown “cement” coats the mass; this are found in areas with cool summers later bleaches to white. Pinholes per- with high humidity such as the San forate this covering in spring as larvae Francisco Bay Area and the Santa Cruz- hatch and emerge through it (Fig. 1). Monterey region, where it is causing Omnivorous and obliquebanded lea- damage to ornamental and fruit trees. frollers sometimes lay their eggs on weeds or leaves as well as on twigs. Damage and management for all spe- Most leafrollers lay eggs in overlapping cies is similar. rows that resemble fish scales (Fig. 2).

Figure 5. Obliquebanded leafroller larva. IDENTIFICATION Larvae of these leafrollers feed inside Leafrollers go through four stages of the protective shelter of leaves that they development—egg, larva (or caterpil- roll or web together (Fig. 3). When dis- larvae are entirely green except for a lar), pupa, and adult (or moth). Adults turbed, the larvae wriggle vigorously black head and small, hard plate just lay eggs in irregular, flat masses on and quickly drop to the ground on a behind the head. As the larva matures, smooth surfaces. The fruittree leafroller silken thread (Fig. 4). Newly hatched its head turns dark brown, and the plate usually lays its egg mass on twigs or fruittree and obliquebanded leafroller becomes tan to olive green (Fig. 5). At

EST OTES Publication 7473 PUniversity of California N Statewide Integrated Pest Management Program Agriculture and Natural Resources September 2010 September 2010 Leafrollers on Ornamental and Fruit Trees

maturity larvae are 3/4 to 1 inch long. LIFE CYCLE Omnivorous leafroller larvae are pale The fruittree leafroller spends the green or light brown with brown or winter in the egg stage and has only 1 black heads and are a little more than /2 one generation a year. Other leafrollers inch long when full grown (Fig. 6). The spend the winter as larva in protected larvae of the light brown apple moth are places on the host and have two or very similar to other leafrollers—pale more generations. to medium green with a light tan head (Fig. 7)—and cannot be reliably dis- The fruittree leafroller overwinters as tinguished from some other leafroller Figure 6. Omnivorous leafroller mature eggs laid on branches or twigs. Eggs larva. species in the field. If you are not in or hatch into tiny larvae from March to as near an area where this pest occurs, it late as mid-May in cooler areas. Larvae is likely another species; however, take feed on leaves for about 30 days then suspicious specimens to your County pupate in a loose cocoon, which they Agricultural Commissioner for identifi- form in a rolled leaf or similar shelter. cation. For the most current information Eight to 11 days later the adult emerges about this invader, visit the California from the pupa. The moths live only Department of Food and Agriculture’s about a week, during which time they Web page, www.cdfa.ca.gov/phpps/ mate and lay eggs. They fly from May PDEP/lbam/lbam_main.html. to June, depending on locality, and in Figure 7. Light brown apple moth larva. When mature, leafrollers pupate within any one area the flight usually lasts a rolled leaf. Silk webbing lines the about three weeks. These moths lay area around each pupa. Adult moths eggs on twigs and branches, and the 1 eggs will remain there until they hatch are about /2 inch long with a wing- 5 7 the next spring. span of about /8 to /8 inch. Wings of leafrollers have a bell-shaped outline Omnivorous, obliquebanded, light when viewed from above. The fore- wings of the fruittree leafroller are brown apple moth, and most other mottled shades of brown and tan with problem leafrollers overwinter pri- gold-colored flecks (Fig. 8) while the marily as larvae in protected places in trees. For example, omnivorous lea- hind wings are whitish to gray. It is Figure 8. Fruittree leafroller adult. difficult to distinguish between adults froller often overwinters in or on old, of various leafroller species, although unharvested fruit, whereas oblique- the omnivorous leafroller has a longer banded leafroller often is found as sec- snout (Fig. 9). ond- or third-stage larvae under bud scales. They pupate in spring, emerge Leafrollers are difficult to distinguish as adults, and sometimes lay their first in the field. However, information re- eggs on weeds. The second generation lated to geographical location and the of these leafrollers, which occurs in plant being attacked can be helpful in June or July, is more likely to occur on determining which species is attacking trees, causing damage later in the sea- the host specimen (Table 1). son than the fruittree leafroller. Figure 9. Omnivorous leafroller adult.

Table 1. Common Leafroller Species, Distribution, and Hosts. Leafroller Where most commonly a pest Most common hosts Fruittree leafroller Warm inland valleys and coast Ornamentals and fruit trees Omnivorous leafroller Warm inland valleys Fruit trees and vines Obliquebanded leafroller Warm inland valleys Fruit trees and vines Light brown apple moth Cool coastal areas Ornamentals, vines, fruit trees, and many other plants Orange tortrix Cool coastal areas Vines, fruit trees, and many noncrop plants Apple pandemis Cool coastal areas Apples and pears

◆ 2 of 4 ◆ September 2010 Leafrollers on Ornamental and Fruit Trees

DAMAGE A white cocoon is an indication that the parasite is present and might provide Leafroller larvae feed on tender, new control. Lacewing larvae, assassin bugs, leaves, giving them a ragged appear- and certain beetles also are common ance; they also roll and tie leaves togeth- predators. Birds sometimes feed on the er with silken threads to form compact larvae and pupae, although they usually hiding places. Some years very large prefer other insects. These natural en- populations develop. In severe cases lar- emies often help to keep leafrollers at low, vae can partially or completely defoliate nondamaging levels, but even if natural trees, and their numerous silken threads enemies are present, large outbreaks of can cover the entire tree and the ground Figure 10. Like the fruittree leafroller, the leafrollers occasionally occur. California oakworm attacks oak trees; below. Also, larvae frequently drop however, it is not a leafroller and is more to the ground on their silken threads Chemical Control likely to be a problem in coastal areas. and can defoliate other plants beneath the trees. However, even completely Sprays for leafrollers seldom are neces- defoliated trees can recover if they are sary. Apply them only when there is otherwise healthy, with the exception of evidence of a damaging leafroller popu- newly planted and first-leaf trees. lation, such as large numbers of larvae early in the spring or large numbers Oaks in the Central Valley can be partic- of egg masses. Because the fruittree ularly hard hit by the fruittree leafroller. leafroller—the most common leafroller Some people mistake this leafroller for attacking oak and other ornamentals— California oakworm (Fig. 10) because of has only one generation a year, by the its prevalence on oaks. However, oak- time trees are severely defoliated, the Figure 11. Pear damaged by a fruittree worm is a more serious pest in coastal caterpillar stage might be almost com- leafroller. areas, while the fruittree leafroller does pleted, and sprays will be of no benefit. the bulk of its defoliation damage to Also, a single defoliation, unless the tree of larval hatching or shortly afterward. oaks in the Central Valley. The two cat- is very small, will not kill the tree. In- To determine this time, inspect twigs erpillars are easy to distinguish—the secticidal oil sprays applied in dorman- showing flushes of new foliage and look fruittree leafroller is green with a black cy for scales and other insects will help for feeding injury and the small caterpil- head, while California oakworm has control leafroller eggs on fruit trees. lars. If you see egg masses, check them yellow, black, and gray stripes on its side regularly for signs of larval exit holes. and a large, brown head. For more in- The microbial insecticide Bacillus thuringi- Fruit trees must be sprayed no later than formation, see Pest Notes: California Oak- ensis, which is sold as a variety of prod- petal fall to prevent larvae from injur- worm listed in the References section. ucts, is effective against the larval stages of leafrollers. Bt, as it is commonly known, ing the young fruit. Use a high-pressure power or hose-end sprayer to force the The larvae of all leafroller species also is a bacterial preparation that causes a material into the leaf rolls and other pro- attack fruit on trees, and young fruit disease in many kinds of caterpillars but tected areas where larvae are found. might fall because of deep feeding does not harm beneficial insects, birds, humans, or other organisms. Leafrollers grooves larvae make just after the fruit REFERENCES has formed. Less severely damaged stop eating within hours after feeding on fruit remain on the tree and develop a sprayed leaf and die several days later. Dreistadt, S. H., J. K. Clark, and M. L. characteristically deep, bronze-colored Thorough spray coverage of the tree is re- Flint. 2004. Pests of Landscape Trees and scars with roughened, netlike surfaces quired for control. Bt is most effective on Shrubs: An Integrated Pest Management that are mostly cosmetic, although the leafroller larvae when they are small (less Guide, 2nd ed. Oakland: Univ. Calif. 1 fruit can become deformed (Fig. 11). than /2 inch long) and usually requires Agric. Nat. Res. Publ. 3359. They do not enter the fruit as do cod- more than one application. Caterpillars ling moth or Oriental fruit moth. must ingest the pesticide to be killed. Bt Flint, M. L. 1998. Pests of the Garden and is available for use on ornamental trees, Small Farm: A Grower’s Guide to Using MANAGEMENT vines, and some fruit and nut trees. Check Less Pesticide. 2nd ed. Oakland: Univ. labels for uses. Spinosad (Monterey Gar- Calif. Agric. Nat. Res. Publ. 3332. Biological Control den Insect Control) is another, organically A number of insects eat leafrollers includ- acceptable insecticide that is effective Swain, S. V., S. A. Tjosvold, and S. H. ing certain tachinid flies and ichneumo- against leafrollers and widely available. Dreistadt. April 2009. Pest Notes: Califor- nid wasps, which parasitize the larvae. nia Oakworm. Oakland: Univ. Calif. Ag- After consuming the leafroller larvae, the Optimum control and a minimum ric. Nat. Res. Publ. 7422. Also available braconid wasp forms a white cocoon next amount of damage by fruittree leafrollers online, www.ipm.ucdavis.edu/PMG/ to the shriveled up worm inside its nest. occur when a spray is applied at the time PESTNOTES/pn7422.html. v

◆ 3 of 4 ◆ September 2010 Leafrollers on Ornamental and Fruit Trees

AUTHOR: W. J. Bentley, UC Statewide University of California scientists and other IPM Program, Kearney Agricultural Center, qualified professionals have anonymously peer reviewed this publication for technical accuracy. The Parlier. ANR Associate Editor for Urban Pest Management managed this review process. TECHNICAL EDITOR: M. L. Flint To simplify information, trade names of products have been used. No endorsement of named products EDITOR: M. L. Fayard is intended, nor is criticism implied of similar products that are not mentioned. This material is partially based upon work ILLUSTRATIONS: Figs. 1-11, J. K. Clark. supported by the Extension Service, U.S. Department of Agriculture, under special project Section 3(d), Integrated Pest Management.

Produced by UC Statewide Integrated Pest Management Program University of California, Davis, CA 95616 This and other Pest Notes are available at www.ipm.ucdavis.edu.

For more information, contact the University of California Cooperative Extension office in your county. See your telephone directory for addresses University of California and phone numbers, or visit http://ucanr.org/ce.cfm. Agriculture and Natural Resources Program

WARNING ON THE USE OF CHEMICALS Pesticides are poisonous. Always read and carefully follow all precautions and safety recommendations given on the container label. Store all chemicals in the original, labeled containers in a locked cabinet or shed, away from food or feeds, and out of the reach of children, unauthorized persons, pets, and livestock. Pesticides applied in your home and landscape can move and contaminate creeks, rivers, and oceans. Confine chemicals to the property being treated. Avoid drift onto neighboring properties, especially gardens containing fruits or vegetables ready to be picked. Do not place containers containing pesticide in the trash or pour pesticides down the sink or toilet. Either use the pesticide according to the label, or take unwanted pesticides to a Household Hazardous Waste Collection site. Contact your county agricultural commissioner for additional information on safe container disposal and for the location of the Household Hazardous Waste Collection site nearest you. Dispose of empty containers by following label directions. Never reuse or burn the containers or dispose of them in such a manner that they may contaminate water supplies or natural waterways.

NONDISCRIMINATION STATEMENT The University of California prohibits discrimination or harassment of any person on the basis of race, color, national origin, religion, sex, gender identity, pregnancy (including childbirth and medical conditions related to pregnancy or childbirth), physical or mental disability, medical condition (cancer-related or genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or service in the uniformed services (as defined by the Uniformed Services Employment and Reemployment Rights Act of 1994: service in the uniformed services includes membership, application for membership, performance of service, application for service, or obligation for service in the uniformed services) in any of its programs or activities. University policy also prohibits reprisal or retaliation against any person in any of its programs or activities for making a complaint of discrimination or sexual harassment or for using or participating in the investigation or resolution process of any such complaint. University policy is intended to be consistent with the provisions of applicable State and Federal laws. Inquiries regarding the University’s nondiscrimination policies may be directed to the Affirmative Action/ Equal Opportunity Director, University of California, Agriculture and Natural Resources, 1111 Franklin Street, 6th Floor, Oakland, CA 94607, (510) 987-0096.

◆ 4 of 4 ◆