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
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.
- Baker, R.S. and F.F. Warren. 1962. Selective herbicidal
action of amiben on cucumber and squash. Weeds 10: 219-224.
- Colby, S.R. 1966. The mechanism of selectivity of amiben.
Weeds 14: 197-210.
- 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.
- Monaco, T.J. and C.H. miller. 1972. Herbicide activity
in close-spaced, pickling cucumbers. Weed Sci. 20: 545-548.
- Noll, C.J. 1977. Weed control in cucumbers in a conventional
planting and in a stale seed bed. Proc. NE Weed Sci. Soc.
- 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.
- Stoller, E.W. 1969. The kinetics of amiben absorption
and metabolism as related to species sensitivity. Plant
Phys. 44: 854-860.
- Union Carbide Agricultural Products Company, Inc., Union
Carbide 1986 Chemical Guide. Page 39.
- Weed control manual 1986 and Herbicide Guide. Published
by Ag. Consultant and Fieldman, A Meister Publication,
1986. Pages 196-97.