L. P. ARAUJO1, L . D. WILLIAMS1, G. OLSON1, T. BASS2, R. D. DINKINS2, T. PFEIFFER1, AND M. BARRETT 1

1U N I V E R S I T Y O F K E N T U C K Y, 2U S D A - A R S - FA P R U

A Novel Kentucky Adapted Red Clover Line Displays Increased 2,4-D Tolerance

Introduction• Red clover (Trifolium pratense)

‣ Legume forage – beneficial when interseedeed with forage grasses

‣ Increases overall quality and yield of the pasture (Frame et al., 1998; Isobe et al., 2014).

• Limitation to greater usage:‣ There are no herbicide options for broadleaf

weed management currently available for use in a clover-grass mixed pasture that will not injure the clover (Green et al. 2006)

UNIVERSITY OF KENTUCKY – INTEGRATED PLANT AND SOIL SCIENCES

Tolerant to 2,4-DMunoz et al. (2015)

Quesenberry et al. (2015)

Adapted to Kentucky’s environment

UK2014 has higher tolerance to 2,4-D than Kenland in greenhouse studies (Lewis 2014)

Objective: Assess the field performance of UK2014, in terms of yield (both with and without 2,4-D treatment) and 2,4-D tolerance.

Materials and MethodsUniversity of Kentucky’s Spindletop Research Farm

• April, 2017 and April, 2018.

RCBD (4 blocks) – Factorial• 1st Factor: Red clover cultivar UK2014 and Kenland

• 2nd Factor: Timing of application (July, August, and October)

• 3rd Factor: 2,4-D Rate (0, 1.12, and 2.24 kg a.e./ha)

Data Collected:

UNIVERSITY OF KENTUCKY – INTEGRATED PLANT AND SOIL SCIENCES

Variable Measurement AssessmentSeason

Total Yield ton/ha Composed of 3 individual harvests, each one performed 1 week after treatments.

Injury 0 = no injury 100 = death 1 week after treatmentRegrowth Percentage of untreated 1 week after harvest

UNIVERSITY OF KENTUCKY – INTEGRATED PLANT AND SOIL SCIENCES

Cultivar 2,4-D Rate(kg a.e./ha)

Season total Yield(ton/ha)

Injury to 2,4-D (0 - 100)

Regrowth(% of untreated)

Kenland 0 7.0 A 0 A 100 A1.12 4.9 C 39 C 72 CKenland

Kenland 2.24 4.7 C 62 D 31 DUK2014 0 7.3 A 0 A 100 AUK2014 1.12 6.8 AB 24 B 92 BUK2014 2.24 6.0 B 37 C 68 Cp-values 0.0390 <.0001 <.0001Std Error 1.3 1.8 3.8

UK2014 (tolerant)

Kenland (sensitive)

Increasing 2,4-D Rate

UNIVERSITY OF KENTUCKY – INTEGRATED PLANT AND SOIL SCIENCES

Discussion

1. UK2014 yield was less reduced less by 2,4-D than yield of Kenland. However, UK2014 yield was reduced by treatment with 2,4-D at 2.24 kg/ha.

2. At the same time, Kenland yield was not reduced more with the rate increase from 1.12 kg/ha to 2.24 kg/ha of 2,4-D amine.

3. Kenland is injured more and regrows less after harvest than UK2014 following 2,4-D treatment.

Conclusions: UK2014 displays increased in tolerance to 2,4-D, compared to Kenland, in a field setting. Applications of 2,4-D, at a high field rate, can cause a reduction in yield of the tolerant line UK2014.

UNIVERSITY OF KENTUCKY – INTEGRATED PLANT AND SOIL SCIENCES

Future Work

Re-selection for higher

2,4-D tolerance

Identification of the

tolerance trait

Grazing study with 2,4-D treatment

(poster #72)

Acknowledgments

Dr. Michael BarrettDr. Randy DinkinsDr. Todd PfeifferTroy BassLinda D. WilliamsGene Olson

Author contact: lucas.araujo@uky.edu