Root suckers are apple tree sprouts that emerge from the rootstock. They grow around the base of the tree. The point of origin of the suckers is the root. This makes them distinguishable from water sprouts, which originate from aboveground parts of the tree. Root suckers cause problems for the main tree in three significant ways:
- They compete with the main tree for water and nutrients.
- They are a prime feeding site for woolly apple aphids.
- They are a potential entry point for fire blight.
M.7, M.9, and G.202 tend to produce numerous root suckers, especially when not planted deep. Very little suckering is characteristic for B.9, G.11, G.16, M.26, M.27, MM.111, and P.18 rootstocks.
Use mechanical or chemical means to control root suckers. To control root suckers mechanically, snap or prune suckers back every year. You may remove suckers during the dormant season when you do regular pruning or at any time of the year. Control root suckers chemically by using a formulation of naphthaleneacetic acid (NAA) (Sucker Stopper Concentrate, Monterey Chemical Company) in the spring. Take care when using NAA, however, as it is also a fruit-thinning agent when used in the spring. To avoid the possible thinning effect of NAA on the main tree from spray drift, delay application until after the regular thinning window, 4 weeks after petal fall.
| Root suckers at the base of an apple tree. Photo: Jon Clements, University of Massachusetts. |
|---|
 |
Resources
Black, B. (2007): Rootstock trials in Utah and the U.S. – Utah State Univ. Extension. http://www.utahhort.org/talks/2007/Black_rootstock%20talk%20revised.pdf
Domoto, P. (2004): Characteristics of apple rootstocks. Iowa State Univ. Extension. http://www.nc140.org/2004/domotorootstock.pdf
Raese , J.T and Tukey, R.B (1995): Chemical control of water sprouts and root suckers of apple and pear. Washington State Univ. Extension. https://pubs.wsu.edu/ItemDetail.aspx?ProductID=13663
Robinson, T., L. Anderson, A. Azarenko, B. Barritt, G. Brown, J. Cline, R. Crassweller, P. Domoto, C. Embree, A. Fennell, D. Ferree, E. Garcia, A. Gaus, G. Greene, C. Hampson, P. Hirst, E. Hoover, S. Johnson, M. Kushad, R. Marini, R. Moran, C. Mullins, M. Parker, R. Perry, J.P. Prive, G. Reighard, C. Rom, T. Roper, J. Schupp and M. Warmund. 2002. Performance of Cornell-Geneva rootstocks in North America NC-140 rootstock trials. Compact Fruit Tree 35(4): 99-102.
Jozef Racsko, The Ohio State University