Skip to main content Accessibility help

Control Recommendations for Black Medic (Medicago lupulina) Based on Growth and Development in Competition with Strawberry

  • Shaun M. Sharpe (a1), Nathan S. Boyd (a1), Peter J. Dittmar (a2), Greg E. MacDonald (a3), Rebecca L. Darnell (a2) and Jason A. Ferrell (a3)...


Strawberries are an important horticultural crop in Florida. Black medic is among the most problematic weeds within the production system. To better coordinate control measures, black medic growth and development while in competition with strawberry was studied. Twelve plants were randomly selected at each of four field sites in Hillsborough County, FL, in 2014. Plants were repeatedly measured over the growing season for stem length and number of primary branches, flower buds, flowers, and seed clusters. Growing degree days (GDD) were calculated (T base=0 C) starting from the hole-punch application of the plastic mulch (October 8, 2014, to October 10, 2014) from weather station data generated from the Florida Automated Weather Network. Strawberry height and width increased consistently across all sites, but black medic growth and development varied considerably. Strawberry suppressed black medic growth up to 1,805 cumulative GDD at three of four sites where black medic remained beneath the strawberry canopy. After 1,805 GDD, the black medic stems still remained below but experienced exponential growth for total stem length and, in turn, flower buds, inflorescence, and immature seed clusters. Ideal clopyralid spray timing based on susceptible plant size was 890 to 1,152 GDD. Optimal hand-weeding time frames would likely occur as the plant stems expand beyond the strawberry canopy (to improve visibility) and before flower production to prevent seed return to the seedbank. First seed production was observed at 1,200 GDD at the earliest site and between 1,966 to 2,365 GDD across all the other sites. Overall, consistent trends were observed across sites, but between-site variability was observed that could not be accounted for by differences in temperature.


Corresponding author

*Corresponding author’s E-mail:


Hide All

Associate Editor for this paper: Hilary A. Sandler, University of Massachusetts.



Hide All
Anonymous (2011) Stinger® supplemental labeling for annual strawberry in Florida. Indianapolis, IN: Dow AgroSciences. 2 p
Bootsma, A (1984) Forage crop maturity zonation in the Atlantic region using growing degree-days. Can J Plant Sci 64:329338
Boyd, NS, Dittmar, PJ (2015) Impact of application time and clopyralid rate on strawberry growth and yield. Weed Technol 29:821826
Clapham, WM, Fedders, JM (2004) Modeling vegetative development of berseem clover (Trifolium alexandrinum L.) as a function of growing degree days using linear regression and neural networks. Can J Plant Sci 84:511517
Dale, HM, Harrison, PJ, Thomson, GW (1965) Weeds as indicators of physical site characteristics in abandoned pastures. Can J Plant Sci 43:13191327
Figueroa, RA, Doohan, DJ (2006) Selectivity and efficacy of clopyralid on strawberry (Fragaria x ananassa). Weed Technol 20:101103
Kadir, S, Sidhu, G, Al-Khatib, K (2006) Strawberry (Fragaria x ananassa Duch.) growth and productivity as affected by temperature. HortScience 41:14231430
Lammerink, J (1968) Genetic variability in commencement of flowering in Medicago lupulina L. in the South Island of New Zealand. NZ J Bot 6:3342
Liu, M, Sun, J, Li, Y, Xiao, Y (2017) Nitrogen fertilizer enhances growth and nutrient uptake of Medicago sativa inoculated with Glomus tortuosum grown in Cd-contaminated acidic soil. Chemosphere 167:204211
McMurray, GL, Monks, DW, Leidy, RB (1996) Clopyralid use in strawberries (Fragariaxananassa Duch.) grown on plastic mulch. Weed Sci 44:350354
Moe, R, Heins, R (1990) Control of plant morphogenesis and flowering by light quality and temperature. Acta Hort 272:8189
Pazmiño, DM, Rodriguez-Serrano, M, Romero-Puertas, MC, Archilla-Ruiz, A, Del Rio, LA, Sandlio, LM (2011) Differential response of young and adult leaves to herbicide 2,4-dichlorophenoxyacetic acid in pea plants: role of reactive oxygen species. Plant Cell Environ 34:18741889
Sharpe, SM (2017) Use of Clopyralid to Control Black Medic (Medicago lupulina) in Florida Strawberry (Fragaria x ananassa) Production. Ph.D dissertation. Gainesville, FL: University of Florida. 130 p
Sharpe, SM, Boyd, NS, Dittmar, PJ (2016) Clopyralid dose response for two black medic (Medicago lupulina) growth stages. Weed Technol 30:717724
Turkington, R, Cavers, PB (1979) The biology of Canadian weeds: 33. Medicago lupulina L. Can J Plant Sci 59:99110
[USDA] U.S. Department of Agriculture (2015) National Agricultural Statistics Service. Accessed: June 19, 2015
[USDA] U.S. Department of Agriculture (2016) Soil Survey Staff, Natural Resources Conservation Service, Web Soil Survey. Accessed: March 30, 2017
Webster, TM (2014) Weed survey—southern states 2014: vegetable, fruit and nut crop subsection. Page 288 in Proceedings of the Southern Weed Science Society 67th Annual Meeting. Birmingham, AL: Southern Weed Science Society
White, SN, Boyd, NS, Van Acker, RC (2012) Growing degree-day models for predicting lowbush blueberry (Vaccinium angustifolium Ait.) ramet emergence, tip dieback, and flowering in Nova Scotia, Canada. HortScience 47:10141021



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed