Skip to main content Accessibility help

Strawberry, black medic (Medicago lupulina), and Carolina geranium (Geranium carolinianum) growth under light-limiting conditions

  • Shaun M. Sharpe (a1), Jialin Yu (a1) and Nathan S. Boyd (a2)


Broadleaf infestations interfere with Florida strawberry production. Broadleaf POST herbicide options applied atop the crop are limited to synthetic auxins and not suitable for conventional multi-cropping and organic systems. Reducing light access and interception during weed emergence may reduce interference. Light-limited growth of two problematic broadleaves, black medic and Carolina geranium, and the most commonly grown strawberry cultivar (‘Florida Radiance’), were examined in the greenhouse. The experimental design was completely randomized, and the trial was repeated. Black medic was susceptible to reductions in incoming solar radiation, wherein reducing the daily maximum available light from 331 to 94 µmol m−2 s−1 reduced leaf number and area by 93% and 89%, respectively. Carolina geranium growth was less susceptible to reduced-light treatments, with leaf area and number each reduced by 66% when light was reduced from 331 to 94 µmol m−2 s−1. Belowground, Carolina geranium biomass was similarly reduced between the 331 and 94 µmol m−2 s−1 treatments. Strawberry was relatively tolerant to shading at 155 µmol m−2 s−1, but further reductions did increase mortality. Shade-induced weed suppression is a promising alternative strategy for conventional and organic Florida strawberry production. Targeted application during periods of weed emergence may play a role within integrated pest management strategies. This approach is most feasible for black medic management but may be useful for Carolina geranium in concert with other strategies.


Corresponding author

Author for correspondence: Nathan S. Boyd, Email:


Hide All
Anonymous (2011) Stinger® supplimental labeling for annual strawberry in Florida. Indianapolis, IN: Dow AgroSciences LLC. 2 p.
Boyd, NS, Dittmar, P (2015) Impact of application time and clopyralid rate on strawberry growth and yield. Weed Technol 29:821826
Chandler, CK, Legard, DE, Dunigan, DD (2000) ‘Strawberry festival’ strawberry. HortScience 35:13661367
Chandler, CK, Miller, DD, Ferree, DC (1992) Shade during July and August reduces growth but not fruiting of strawberry plants. HortScience 27:1044
Darnell, RL (2003) Strawberry growth and development. Pages 310 in Childers, N, ed. The Strawberry: A Book for Growers, Others. Gainesville, FL: Dr. Normal F. Childers Publications 246 p
Fernandez, GE (2001) Fall-applied rowcovers enhance yield in plasticulture strawberries. HortTechnology 11:440444
Ferree, DC, Stang, EJ (1988) Seasonal plant shading, growth, and fruiting in ‘Earliglow’ strawberry. J Am Soc Hortic Sci 113:322327
Gast, KLB,Pollard, JE (1991) Rowcovers enhance reproductive and vegetative yield components in strawberries. HortScience 26:14671469
[IFAS] Institute of Food and Agricultural Sciences (2018) Florida Automated Weather Network, University of Florida. Accessed: December 13, 2018
Interrante, SM, Muir, JP, Rosiere, RE, Rhykerd, RL (2004) Effects of shade and Rhizobium inoculation on herbage of black and button medics. Texas J Agric Nat Resour 71:5771
Liston, A, Cronn, R, Ashman, TL (2014) Fragaria: a genus with deep historical roots and ripe for evolutionary and ecological insights. Am J Bot 101:16861699
Norsworthy, JK, Ward, SM, Shaw, DR, Llewellyn, RS, Nichols, RL, Webster, TM, Bradley, KW, Frisvold, G, Powles, SB, Burgos, NR, Witt, WW, Barrett, M (2012) Reducing the risks of herbicide resistance: best management practices and recommendations. Weed Sci 60:3162
Pritchard, MK, Warren, GF (1980) Effect of light on the response of tomato (Lycopersicon esculentum) and two weed species to metribuzin. Weed Sci 28:186189
Sharpe, SM (2017) Use of clopyralid to control black medic (Medicago lupulina) in Florida strawberry (Fragaria xananassa) production. Ph.D dissertation. Gainesville, FL: University of Florida. 131 p.
Sharpe, SM, Boyd, NS (2018) Black medic (Medicago lupulina) emergence and emergence predictors within Florida strawberry fields. Weed Sci, 10.1017/wsc.2018.69
Sharpe, SM, Boyd, NS, Dittmar, PJ (2016) Clopyralid dose response for two black medic (Medicago lupulina) growth stages. Weed Technol 30:717724
Sharpe, SM, Boyd, NS, Dittmar, PJ, MacDonald, GE, Darnell, RL (2018a) Clopyralid tolerance in strawberry and feasibility of early applications in Florida. Weed Sci 66:508515
Sharpe, SM, Boyd, NS, Dittmar, PJ, MacDonald, GE, Darnell, RL (2018b) Effect of temperature on clopyralid safety in strawberry. Weed Technol 32:347351
Sharpe, SM, Boyd, NS, Dittmar, PJ, MacDonald, GE, Darnell, RL, Ferrell, JA (2018c) Control recommendations for black medic (Medicago lupulina) based on growth and development in competition with strawberry. Weed Sci 66:226233
Sharpe, SM, Boyd, NS, Dittmar, PJ, MacDonald, GE, Darnell, RL, Ferrell, JA (2018d) Spray penetration into a strawberry canopy as affected by canopy structure, nozzle type, and application volume. Weed Technol 32:8084
Singh, A, Syndor, A,Deka, BC, Singh, RK, Patel, RK (2012) The effect of microclimate inside low tunnels on off-season production of strawberry (Fragaria × ananassa Duch.). Sci Hortic 144:3641
Stoller, EW, Myers, RA (1989) Response of soybeans (Glycine max) and four broadleaf weeds to reduced irradiance. Weed Sci 37:570574
[USDA-NASS] U.S. Department of Agriculture-National Agricultural Statistics Service (2019) Data and Statistics. Accessed: February 19, 2019
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
Whitaker, VM, Boyd, NS, Peres, NA, Noling, JW, Renkem, J (2017) Strawberry production. Pages 293312 in Vallad, GE, Smith, HA, Dittmar, PJ, Freeman, JH, eds. Vegetable Production Handbook of Florida 2017–2018. Gainesville, FL: University of Florida. 411 p.
Whitaker, VM, Chandler, CK, Peres, N, Cecilia, M, Nunes, N, Florida, S, Avenue, EF, Pierce, F, Sims, CA (2015) Sensation™ ‘Florida127’ strawberry. HortScience 50:10881091


Strawberry, black medic (Medicago lupulina), and Carolina geranium (Geranium carolinianum) growth under light-limiting conditions

  • Shaun M. Sharpe (a1), Jialin Yu (a1) and Nathan S. Boyd (a2)


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