Sustainable Agriculture A program of the National Center for Appropriate Technology • 1-800-346-9140 • www.attra.ncat.org Flea Beetle: Organic Control Options By George Kuepper, This publication focuses on organic control of fl ea beetles, one of the more serious vegetable crop pests. NCAT Agriculture Cultural and biological options are discussed along with alternative pesticidal materials. Specialist Published March 2003 Updated by Rex Dufour, NCAT Agriculture Specialist April 2015 ©NCAT IP389 Contents Introduction ............................1 Cultural/Physical Controls ....................................2 Biological Control .................2 Alternative Pesticides ..........3 References ...............................4 Further Resources .................4 Typical damage of fl ea beetle on brassicas—likely the Crucifer Flea Beetle . Photo: Rex Dufour, NCAT Introduction lea beetles are one of the most diffi cult-to- considered general feeders, though many species manage pests of eggplant and cole crops. attack only one plant or closely related kinds of FTh ey are also a problem on seedlings of plants (Metcalf and Metcalf, 1993). tomatoes, potatoes, peppers, turnips, radishes, Life history varies somewhat with species, but and corn. Th ere are various genera and species most appear to pass the winter in the adult stage, of fl ea beetles, all members of the Chrysomeli- ATTRA (www.attra.ncat.org) sheltering under plant debris in the fi eld, fi eld is a program of the National dae family. Th e adults are active leaf-feeders that margins, and adjacent areas. Th e adults emerge in Center for Appropriate Technology can, in large numbers, rapidly defoliate and kill (NCAT). The program is funded spring and may feed on weeds and less-desirable through a cooperative agreement plants. Symptoms of fl ea beetle feeding are small, vegetation until crop plants become available. As with the United States Department rounded, irregular holes; heavy feeding makes a result, they are frequent pests in seedbeds and of Agriculture’s Rural Business- leaves look as if they had been peppered with Cooperative Service. Visit the on new transplants (Metcalf and Metcalf, 1993). NCAT website (www.ncat.org) fi ne shot. Some species also vector serious dis- Th ey may become especially troublesome when for more information on eases such as potato blight and bacterial wilt of weedy areas begin to "dry up." Flea beetles cause our other sustainable agriculture and corn. Further damage may be done by the larvae, the greatest damage by feeding on cotyledons, energy projects. which feed on plant roots. Some fl ea beetles are stems, and foliage (Hines and Hutchinson, 1997). www.attra.ncat.org Page 1 In organic systems, the preferred approaches to preferred by the pest—at 6- or 12-inch intervals pest management are those that enhance the among cole crops. In one trial, this measurably diversity of the farm system, such as cover crop- reduced damage to broccoli (Byczynski, 1999). ping, rotation, and interplanting; those that use special knowledge of pest biology, such as delayed Row-cover materials such as Reema™ can be used planting; and those that take advantage of exist- to cover seedlings and provide a barrier to adult ing on-farm resources. Th ese approaches are typi- beetles. It is advisable to get the row cover in place fi ed by cultural and biological controls, which will at or before emergence for maximum protection. be discussed fi rst. Alternative pesticides, while Th e covers can be removed once the pest popu- frequently necessary for some crop pests and con- lation subsides (Ellis and Bradley, 1992). To be ditions, can be treated as "rescue chemistry" to most eff ective, row covers should be used in con- be used when and if other strategies fall short. junction with a planned crop rotation in which the crop to be protected follows a non-suscepti- ble crop. Th is reduces the chance that pests will Cultural/Physical Controls emerge under the row cover (Caldwell, 1998). Flea beetles are favored by stable, warm spring ATTRA has additional information on row cov- weather and hampered by alternating periods ers, including manufacturers and distributors, in of hot and cold temperatures with intermittent the publication Season Extension Techniques for rains. Seedlings of crops are most vulnerable to Market Gardeners. Related ATTRA fl ea-beetle feeding when stressed, particularly by Growers report some level of fl ea-beetle control Publications inadequate moisture. Providing good nutrition using white and yellow sticky traps (Byczynski, www.attra.ncat.org and favorable growing conditions aids in shorten- 1999; Anon., 1996). Reference is made to indi- ing the vulnerable early-growth stages and helps vidual traps placed every 15 to 30 feet of row. Bug Vacuums for plants survive fl ea-beetle attack. Th e literature Encircling the fi eld with continuous sticky tape Organic Crop suggests that organic fertilization may make crops Protection less attractive to fl ea beetles (McKinlay, 1992). is also mentioned. Sources of sticky traps include ARBICO and Golden Harvest Organics (see Cole Crops and Other Brassicas: Organic Because the pest is so mobile, and because so many Further Resources). Production genera and species are involved, crop rotation, by itself, has little eff ect as a control strategy. How- Since the adults overwinter in plant debris, there Organic Cotton ever, living mulches or polycultures are known to is value in sanitation procedures that destroy ref- Production reduce fl ea-beetle damage (McKinlay, 1992; Anon., uge sites. Plowing or rototilling weeds and crop residues in the fall is often recommended, as is Organic IPM Field 2000). One reason for this is that the individual crop Guide plants are not silhouetted against a bare-soil back- destruction of grassy and solanaceous (tomato ground and are less obvious to the pest (McKin- family) weeds adjacent to the fi eld (Flint, 1990). Specialty Lettuce Unfortunately, these procedures are often in con- and Greens: Organic lay, 1992). Th e ATTRA publication Companion Planting elaborates further on this subject. fl ict with good sustainable practices that strive to Production maintain soil cover and fi eld buff ers. When such Season Extension Trap cropping, in which attractive plant spe- confl icts occur, growers can view sanitation pro- Techniques for Market cies are planted near the main crop to draw the cedures as transitional strategies only and look for Gardeners pest away, off ers some possibilities for fl ea-bee- more sustainable practices to use in the future. tle management. Apparently the most practical trap crop is Chinese Southern Giant Mustard Anecdotal reports have suggested that catnip (Brassica juncea var. crispifolia), seed of which is might repel fl ea beetles. Research by organic gar- widely available. Research has shown that plant- deners in 1997 failed to confi rm this information, ing this trap crop about every 55 yards between however. Th e gardeners reported that catnip used rows of cabbage, broccoli, or caulifl ower (or as a as a mulch or sprayed as an extract tea did a gen- border around the fi eld) can do an exceptional erally poor job of repelling the pest (Long, 1998). job of protecting them. To retain eff ectiveness, reseeding of the trap crop may be necessary, Biological Control especially if the pest destroys the fi rst planting. In healthy agroecosystems, there are populations Th e trap is less eff ective in protecting crops that of benefi cial predators and parasites that work to are almost as attractive to fl ea beetles as Giant control the number of fl ea beetles and other pests. Mustard is, such as Nappa cabbage, gai choy, One example is Microcotonus vittage Muesebeck, and choy sum (Chaput, 1999). a native braconid wasp that kills the adult fl ea Another approach to trap cropping is to interplant beetle and sterilizes the female fl ea beetle (Hines radishes—Chinese Daikon and Snow Belle are and Hutchinson, 1997). Growers can manage the Page 2 Flea Beetle: Organic Control Options diversity of their farms and gardens to support Not a botanical and not often populations of benefi cials. Specifi c information mentioned in this regard, dia- on such strategies is provided in the ATTR A pub- tomaceous earth has been lication Farmscaping for Biological Control. observed to reduce fl ea-beetle populations and is sometimes Commercial formulations of entomopathogenic recommended (Anon., 1999; nematodes are eff ective agents for controlling fl ea Spring and Day, no date). beetles (Ellis and Bradley, 1992). Applied to the soil, the nematodes attack the beetle's larval stage, Th e kaolin-clay-based product reducing root feeding and helping to prevent the Surround™ has undergone some next cycle of adults from emerging. ATTRA’s preliminary evaluation for fl ea- Ecological Pest Management Database (https:// beetle control on eggplant. While attra.ncat.org/attra-pub/biorationals/index.php) eff ective in reducing fl ea-beetle has information about formulations of benefi cial damage, Surround™ degraded nematodes. Search in “Active Ingredients” under fruit yield and quality; there also Steinernema or Heterorhabditis. were problems removing the clay- An assassin bug preying on a fl ea beetle, residue coating from the fruit. with typical fl ea beetle damage on Alternative Pesticides Th e use of this product will likely eggplant leaf. Likely Western Potato Flea be limited to the early part of the Beetle. Photo: Chris Hay Botanical pesticides recommended for control- season, before fruit set (Maletta et ling fl ea beetles include neem, rotenone, pyre- al., 2002). thrin, sabadilla, and formulations of these in some combination (Ellis and Bradley, 1992). Th e Uni- Fields should be regularly monitored to deter- versity of California mentions insecticidal soap mine if and when any pesticidal agents should be as an organic option for fl ea beetles, but indi- applied. Th is is especially critical with fl ea beetles, cates that it "may provide partial control" only since a small population can do signifi cant dam- (Anon., 1997; Nielsen, 1997).