Application for Control of Root Suckers 



Root suckers are more difficult to control than water sprouts 

 because they originate from roots below the soil surface and their 

 source is not treated directly. Sucker control is achieved by 

 killing the suckers sprayed and by the translocation of the NAA 

 in the Tre-Hold downward through the suckers. 



Clumps of suckers, with their height varying within the clump, 

 proliferate from stubs created by~ pruning . iheretore , good coverage 

 of Tre-Hold on all suckers within each cTump appears necessary for 

 their control. Spray coverage also is facilitated by the control 

 of weeds with herbicides. We found that spraying the grass, weeds 

 and suckers with paraquat 2 weeks prior to the application of 

 Tre-Hold effective for increasing sucker control. This treatment 

 killed the grass and weeds and "injured" the leaves on suckers. 

 The injury of the leaves made good spray penetration into clumps 

 of suckers easier and yet allowed enough leaf surface to remain 

 for effective absorption. 



Adequate spray coverage of dense sucker populations is likely 

 to be difficult when using a tractor-mounted weed sprayer and boom 

 since the sprayer should be used at low pressure (10-20 psi) to 

 avoid fruit thinning or ripening from spray drift. Better spray 

 coverage can be obtained with hand-carried or back-pack sprayers 

 because the nozzle of the sprayer can be thrusted into clumps of 

 suckers. Merely directing the spray at the suckers fails to pro- 

 vide adequate coverage and sucker control . Even following the 

 procedure for increasing spray penetration within clumps of suckers 

 may not eliminate the need of repeat annual applications of the 

 Tre-Hold to achieve complete sucker control. 



Avoid spraying Tre-Hold on windy days to reduce drift of fine 

 spjay particles. Do not apply Tre-Hold when the temperature exceeds 

 85 F. because volatilization of the NAA can cause leaf damage 

 or fruit ripening on early maturing varieties. 



The Tre-Hold mixture is very expensive and to reduce the expense 

 of application apply on suckers beyond the reach of the mower. The 

 sucker population is generally most dense near the tree trunks and 

 most troublesome inside the wire mouse guards. Therefore, in gen- 

 eral, the spray should be limited to these areas. 



The most effective timing of the Tre-Hold application is when 

 the suckers are actively growing. The suckers should have been 

 pruned during the dormant season prior to treatment to shorten their 

 height and to force succulent growth. Since the Tre-Hold mixture 

 contains 10,000 ppm NAA the application should be delayed until 

 about 4 weeks after petal fall to eliminate the possibility of 

 fruit thinning and leaf injury. 



