Field Bindweed in California

ers, seeds, or seed capsules. The most Field bindweed in California destructive organisms are the seed beetles (Bruchidae), especially Sperrnopha- The outlook for biological control gus sericeus (Geoffroy). In Greece, smut caused by the fungus Thecophora se- minis-convolvuli (Desmaz.) Lioro infects Sara S. Rosenthal 0 Lloyd A. Andres 0 Carl B. Huffaker up to 17 percent of the seeds. Stem and root feeders. The remain- ing Mediterranean natural enemies attack the stems and roots. The agromyzid fly, Melanagromyza albocilia Hendel, is Biological control is seldom attempt- fornia, we have found a pattern that the most widespread stem borer. The ed against weeds on cultivated lands, may be used to help select the most pyralid moth, Noctuelia floralis because herbicides generally provide suitable European organisms for bio- (Huebner), attacks stems and roots ex- economical, efficient control, and farm- logical control. ternally. The most common root feeder ing practices may interfere with the Our discussion focuses on such spe- is the larva of the flea beetle, Longitar- biological agents. Field bindweed, how- cies and excludes many insects attract- sus pellucidus Foudras (or very near). ever, reproduces from seeds that may ed to the flowers for pollen or nectar as The adult feeds on the leaves. remain alive in the soil for more than 40 well as many crop pests for which field years and from an extensive perennial bindweed is an alternate host. For ex- California plant feeders root system. Control by cultivation or ample, we did not include the spider Foliage feeders. As might be expect- chemicals is difficult, at best. A search mites Tetranychus cinnabarinus Bois- ed, field bindweed has fewer natural for biological control agents therefore duval and T. urticae Koch, which are enemies in California that it has in its seemed warranted. Even if such agents very common and damage field bind- place of origin. The natural enemies of were effective only on field bindweed weed leaves in late summer. Various the native North American morning glo- growing along roadsides and in other sucking insects in the families Aphidi- ries, however, are more numerous and uncultivated areas, they would reduce dae, Cercopidae, and Pentatomidae feed tend to specialize in much the same way the weed’s potential for further invasion on field bindweed leaves, stems, and as species associated with bindweed of cultivated land. A cooperative U.S. seed capsules, respectively, but they and morning glories around the Medi- Department of Agriculture and Univer- also feed on nearby crop plants. Natural terranean. The previously mentioned sity of California project was begun in enemies that could damage commer- leaf miner and plume moth are distrib- 1970 to find biological agents for control cially valuable plants, primarily sweet uted worldwide and already occur in of field bindweed. potato, Ipomoea batatus (L.) Lam., or California on both field bindweed and Between then and 1979, Rosenthal ecologically valuable plants such as na- Calystegia spp. They have been consid- and a co-worker, Gary Buckingham, tive Calystegia spp. cannot be intro- ered as possible biological control collected arthropods and diseases that duced into the state. While hedge bind- agents for field bindweed and hedge attack field bindweed and its close rela- weed, Calystegia sepium (L.) R. Brown, bindweed in the eastern United States, tives in its native habitat, the Mediter- is a serious pest in the eastern United but both feed readily on sweet potato ranean area and Middle East. Trips were States, the native California morning and native morning glories. Therefore, made to Italy, Greece, the Iberian Penin- glories in this genus are not considered they cannot be used in California, and sula, Turkey, and Iran and to several troublesome. Two of them are rare their spread or augmentation anywhere other European countries. At each loca- plants that are under review for protec- in North America would seem unwise. tion, plants were inspected for damage, tion as endangered or threatened spe- A chrysomelid leaf miner, Brachycor- and arthropods were collected with an cies. yna delbrosa, can be numerous in the aspirator, hand-picked, or swept from leaves of woolly morning glory, Calyste- the plants with a net. Seeds and whole European plant feeders gia malacophyla (Greene) Munz, but it crowns were collected, from which or- Foliage feeders. About 80 percent of appears unable to live in the thinner ganisms were later reared or dissected. the natural enemies of field bindweed leaves of field bindweed. Lepidopterans The foreign work also included pre- in the Mediterranean are associated that feed on a variety of plants, such as liminary biological and host specificity with the foliage. Some of these, particu- the omnivorous leaf tier, Cnephasia lon- studies of the most promising biological larly Bedellia somnulentella Zeller (Lep- gana (Haworth), attack field bindweed control agents, using: bouquets of test idoptera: Lyonetiidae), are internal leaf in California, but no host-specific or plant material in %-pint (0.2-liter) card- miners. Externally feeding plume moth specialized Lepidoptera have been asso- board cartons; whole, small plants caterpillars (Pterophoridae), primarily ciated with the weed as they are in grown in peat pellets or small pots; Emmelina [Oidaematophorus) mono- Europe. Tortoise beetles (Cassidinae) outdoor plants in field cages; and ran- dactyla (L.) and leaf beetles (Chrysome- are commonly found on native morning domly planted test species in an experi- lidae), are most commonly seen on fo- glories but are seldom seen attacking mental garden in Greece. We conducted liage in the early half of the growing field bindweed. A gall mite, Eriophyes some final host specificity screening us- season; other lepidopterous defoliators sp., forms leaf galls on Calystegia ful- ing test plant bouquets in cardboard become more abundant later in the crata (Gray) Brummitt but is not found cartons in the US.Department of Agri- year. The most widespread moth of this on field bindweed. culture quarantine laboratory in Alba- latter group is Tyta luctuosa (Denis & Leaf spotting has occasionally been ny, California. Since 1980, Rosenthal Schiffermueller) (Noctuidae). Gall mites seen on field bindweed, but no fungus has also collected natural enemies of (Eriophyidae) distort and gall the leaves has yet been isolated from such spots. field bindweed and the closely related and buds. The most common foliar dis- Rust caused by the fungus Puccinia con- wild morning glories in the genus CaJys- ease is powdery mildew caused by the volvuli (Pers.) Cast. is seen on leaves of tegia in California. By comparing the fungus Erysiphe convolvuli DC. six Calystegia spp. but not on field bind- kinds of natural enemies associated Flower and seed feeders. Some 17 weed, even though it is considered to be with field bindweed and its close rela- percent of the Mediterranean natural a host of this fungus. tives in the Mediterranean and in Cali- enemies of bindweed feed on the flow- Continued on page 22 1 8 CALIFORNIAAGRICULTURE, SEPTEMBER-OCTOBER 1983 Range improvement, cont’d the annuity. If the yield increase cannot The advantage of the equivalent an- be quantified, this will be a subjective nuity approach is the ease of adjusting evaluation. the benefits to evaluate potential values The possible sale of firewood, now a of conversion, production, and livestock profitable product for many ranchers, prices. Estimation of the net present will affect the method of improving value of these improvements and the wooded ranges. After the wood is har- subsequent sensitivity should give the vested, the area can be seeded for im- same answer. The annuity method is proved range capacity. The Hopland suggested only in those instances where Field Station has had a one-time yield of the yields and prices are not known and 12% cords per acre with a conservative estimates of the benefits are very uncer- stumpage price of $5 per cord. Although tain. In these cases subjective evalua- the money from selling firewood may tion will be assisted by the relatively finance the seeding costs, the firewood easy, equivalent annuity method. and seeding should be evaluated sepa- rately for profitability. Costs of seeding after firewood harvest convert to an Kent D. Olson is Economist, and Theodore E. equivalent annuity of $1.09 per acre Adorns, Jr.. is Wildlands Specialist, Cooperative (table 2), which should be compared Extension, University of California, Davis; and Alfred H. Murphy is Superintendent, Hopland with expected benefits and variations as Field Station, and Specialist, Agronomy and described. Range Science. Field Bindweed, cont’d Flower and seed feeders. The bru- Further tests conducted with the leaf chid beetle Megacerus impiger Horn fre- beetle in the quarantine facility at Alba- quently attacks seeds of all the Califor- ny, however, indicated that this beetle nia Calystegia spp. but only rarely is could feed and reproduce on several found in field bindweed seeds. The North American sweet potato varieties. smut found in Greece also occurs in The gall mite Aceria convolvuli Na- northern North America but is not lepa, from Greece, which attacks field found in California. bindweed buds and leaves, did not feed Stem and root feeders. No California on American sweet potato varieties in organisms are associated with field laboratory tests, but tests on American bindweed stems, but the cecidomyid morning glories are not complete. The fly, Lasioptera convolvuli Felt, forms powdery mildew appears to attack Con- stem galls on western morning glory, volvulus and Calystegia spp. Neither Calystegia occidentalis (Gray) Brum- natural enemy has been thoroughly mitt. The sweet potato flea beetle, studied yet, but both organisms, or at Chaetocnerna confinis Crotch, like its least some closely related organisms, European counterpart, Longitarsus offer promise of being specific. pellucidus, feeds on roots in its larval In conclusion, because some Ameri- stage and on leaves in its adult stage.

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