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Cucurbit Genetics Cooperative Report 12:7-8 (article 3) 1989

Tolerance of Cucumber to Chloramben Herbicide

Jack E. Staub and Linda K. Crubaugh

USDA, ARS Department of Horticulture, University of Wisconsin, Madison, WI 53706

Lack of an efficacious chemical weed control system is a major factor which limits yield in commercial cucumber (Cucumis sativus L.) production in the United States. This is particularly true of once-over, mechanically-harvested acreage where uniform emergence and flowering, and plant growth at close spacings can be dramatically affected by weed competition (4).

Bensulide, DCPA, CDEC, naptalam, paraquat, trifluralin and chloramben are currently registered for use in commercial cucumber production in the United States (9). Bensulide, CDEC, and naptalam often give poor weed control (5, 6) and DCPA causes severe damage when surface-applied prior to crop emergence (4). Paraquat, being a contact herbicide, is only suitable for removing weeds for seedbed preparation and does not provide control for an extended period of time (9). Moreover, since the suggested safe use of chloramben requires the addition of activated charcoal as a saftening agent (8), which adds costs of time and materials, it has received limited use among growers (Personal communication, H.J. Hopen, 1988).

Given these restrictions and/or the poor performance of these herbicides, it would be useful to identify germplasm possessing herbicide resistance or tolerance. Although chloramben (3-amino-2, 5-dichlorobezoic acid) provides excellent grass and broadleaf weed control (8,9), crop tolerance and genotypic variability is low (1, 3). We felt it prudent to survey the U.S. cucumber collection for chloramben tolerance. If tolerant accessions were identified, this would allow for the development of a resistant population for use in breeding programs.

The germplasm collection was surveyed by planting 25 seeds of each accession (753) in each of 20 replications arranged in a randomized complete block design at Hancock, WI (sandy loam soil) in 1987. After planting, chloramben 75DF was surface applied at 6.72 kg/ha to half of the plots. After 12 hours, 13 mm of water was applied through overhead sprinkler irrigation. Treated seedlings were compared to controls 1 and 3 weeks after emergence, and rated for chloramben injury on a 10 point scale (1=seedling death, 5=moderate to severe, and 10=no injury). All plants showed some injury. Plants with mean values of 7 to 9 (Table 1) were classified as tolerant. These plants were transplanted to the greenhouse and random-mated.

The mechanism of resistance and/or tolerance to chloramben in these plants is unclear. Several mechanism have been proposed to explain tolerance to chloramben. Stoller (7) suggests that plants tolerant to chloramben sustain higher internal chloramben concentrations and conjugate absorbed chloramben more rapidly than susceptible species. Colby (2) hypothesized that tolerance is a function of the binding of the chloramben in the roots of more tolerant species. In this scenario, chloramben bound in the roots reduces phytotoxicity in the leaves in tolerant plants; hence, there is less translocation of chloramben.

Our objective was to develop a population tolerant to chloramben form which inbred lines with acceptable horticultural characteristics could be developed. An elite population is being develop form chloramben tolerant lines (Table 1) through recurrent half-sib family selection. After initial selection, near-isogenic tolerant and susceptible lines will be developed. Not only will these lines be of value in hybrid production, but near-isogenic lines may allow for further elucidation of tolerance mechanisms.

Table 1. Plant introductions in the U.S. cucumber germplasm collection which were classified as tolerant to chloramben herbicide ( 6.72 kg/ha) at Hancock, WI in 1987.

PI no.


Varietal Name









Lange Groene Broei











Peoples Rep. China

Tsin Sanz Yen 15919






Green Spot Super

Literature Cited

  1. Baker, R.S. and F.F. Warren. 1962. Selective herbicidal action of amiben on cucumber and squash. Weeds 10: 219-224.
  2. Colby, S.R. 1966. The mechanism of selectivity of amiben. Weeds 14: 197-210.
  3. Miller, Jr., J.C., D. Penner and L.R. Baker. 1973. Basis for variability in the cucumber for tolerance to chloramben methyl ester. Weed Sci. 21: 207-211.
  4. Monaco, T.J. and C.H. miller. 1972. Herbicide activity in close-spaced, pickling cucumbers. Weed Sci. 20: 545-548.
  5. Noll, C.J. 1977. Weed control in cucumbers in a conventional planting and in a stale seed bed. Proc. NE Weed Sci. Soc. 31: 248-251.
  6. Romanowski, R.R. and J.S. Tanaka. 1965. An evaluation of herbicides for use with cucumber (Cucumis sativus) and watermelon (Citrullus vulgaris) in Hawaii. Hawaii. Hawaii Ag. Exp. Stat. Prog. Rpt. 144, 30 pages.
  7. Stoller, E.W. 1969. The kinetics of amiben absorption and metabolism as related to species sensitivity. Plant Phys. 44: 854-860.
  8. Union Carbide Agricultural Products Company, Inc., Union Carbide 1986 Chemical Guide. Page 39.
  9. Weed control manual 1986 and Herbicide Guide. Published by Ag. Consultant and Fieldman, A Meister Publication, 1986. Pages 196-97.
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