How to Get Rid of Plum Tree Shoots and Suckers for a Healthier Tree

Many types of fruit trees produce suckers around the base of the tree. Crown suckers arise in the area immediately surrounding the tree trunk. Root suckers can arise from roots further away from the trunk. Insect pests like wooly apple aphid can live in suckers around trees, and diseases like fire blight can get in through them. If suckers are profuse they interfere with in-row weed management and can absorb systemic herbicides such as glyphosate. Some rootstocks used for fruit trees such as M. 7 for apples and Mazzard for cherries are genetically predisposed to produce suckers. M. 9 clone RN-29 is more inclined to sucker than other M. 9 clones. In some cases, sucker growth is a symptom of partial incompatibility between the rootstock and scion. Suckers can also result from injury to the crown such as extreme cold or mechanical injury. Whatever the cause, managing suckers takes time and expense.

Sucker management falls into two general categories: mechanical and chemical. Each approach has merit depending on the orchard situation.

When onlya few suckers are present, they are often removed during dormant pruning. In severe cases, sickle bar style mowers or gas-powered hedge shears have been used to remove suckers. But sometimes, when suckers are cut off mechanically, more than one new shoot can grow from a single sucker, which makes the problem worse. Mechanical control is also expensive and labor intensiveand may have to be done more than once per year. Related to mechanical control is control by heat. In a USU trial, burning suckers with a propane torch provided good control that lasted several weeks. This may be an effective approach for a few suckers here and there. To treat an entire block with a torch, the vehicle would have to move very slowly and use a lot of propane. Care would also need to be taken to not damage irrigation tubing.

Chemical control of suckerscan be effective andis less labor intensive than mechanical control. Many acres can be treated in a day by a single operator. Chemical controls for suckers can be grouped into three categories: Plant growth regulators, herbicides, and desiccants.

Commercial fruit growers have long used a synthetic auxin,Naphthalene Acetic Acid (NAA),to reduce the growth of suckers. It is the same plant growth regulator (PGR) that is used to thin fruit, but it is used at a different time and in a different amount. Because NAA will cause a thinning response, application must be delayed until a month after petal fall. This allows time forthe fruit to set and become less sensitive to NAA. Still, it should be applied with nozzles that make big droplets at a low pressure (10–20 psi) to keep it from drifting. A specific formulation of NAA (Tre-Hold A-112™)is registered for this use. For apples an 0. 5% to 1% solution of NAA should reduce the growth of root suckers.

Some specific contact herbicides are registered for sucker managementfor fruit trees. Even though these are registered to kill or stop sucker growth, they are still herbicides and can hurt trees, especially young trees whose bark is still green and not corky. Therefore, care must be taken during application to not treattree trunks. Young trees should have trunk wraps installed before application ofherbicide products. Contact herbicides are better than other types of herbicides because they can kill weeds that have come up since the spring applications.

When using herbicides to get rid of sucker plants, it’s best to spray them only when the wind is calm and with low pressure and big droplets. Low drift nozzles are preferred. The use of off-center nozzles may lead to overspray on trunks. For these contact herbicides, good coverage of the foliage is essential. Thus, sufficient water must be sprayed to thoroughly wet the leaves. Control is best when the suckers are still youngand succulent, and not woody.

Paraquat(Gramoxone™) is a caustic, non-systemic, post-emergent herbicide that burns green vegetation. Paraquat is quickly taken up by green plant cells and reacts with photosynthesis to make superoxides, which destroy plant cells. Paraquat is a restricted use pesticide that can only be mixed and used by certified pesticide applicators. It is very dangerous to humans. It provides good burn down of suckers at the higher rates.

Glufosinate (Rely280™, Cheetah™) is another contact herbicide that is registered for sucker management. It is the slowest acting of the herbicide products included in this fact sheet. It can take 20-25days to reach the level of control provided by the other herbicides in 10-14 days.

Carfentrazone-ethyl (Aim EC) is registered for sucker control in fruit trees. Aim must be applied using a hooded sprayer to minimize the opportunity for drift. Also, it must be mixed with an appropriate rate of a nonionic surfactant or crop oil concentrate. Aim works well to control suckers when they are green and not woody, but the risk of damage from drift makes it a less desirable option.

Pyraflufen-ethyl (Venue) is a contact herbicide for post-emergent control of a range of broadleaf weeds. It also has a supplemental label for control of suckers in fruit trees. It is fast acting and effective at the 4 fl. oz/a rate. Cherry suckers are more susceptibleto Venuethan apple.

Table 1. Use patterns for herbicides registered for sucker control in tree fruits. Check product labels for specific use information.

We just recently learned about a material that is used in other places to keep tree fruits and nuts from sprouting. Urea Ammonium Nitrate (UAN) is a liquid fertilizer that is a powerful desiccant. It is not registered as a pesticide. It can be purchased in co-op agronomy centersin the Intermountain West. When sprayed on suckers in the spring it desiccates the succulent foliage and stunts growth. Since it is 32% nitrogen, by weight, it also provides additional nitrogen when applied for sucker control.

We tested UAN against NAA, paraquat, and burning with either a propane torch or a water control in 2019. The trial was conducted on a block of ‘Gala’ on EMLA. 7 rootstocks at the Kaysville Research Farmin Kaysville, Utah. The trees were planted in 2006and had a long history of extensive root suckering. In the early spring we cut off all the existing suckers with hedge shears. That made sure that the suckers would grow back, and it made sure that none of the treatments had suckers when the trial started. Treatments were assigned to trees in five orchard rows in a completely randomized designwith four replications. Applications were made on four dates in 2019: April 30, May 3, May 9 and May 20. The first treatments were made when initial sucker growth ranged between three and six inches. Treatments were Water, 1% NAA, Paraquat, UAN, and burning with a propane torch. NAA and Paraquat were mixed immediately prior to use. All liquid treatments were applied with a one-gallon pump up sprayer and the suckers were sprayed to runoff. Our propane torch burned the area under the tree until none of the suckers had any leaves on them.

We evaluated the treatments on May 9, June 10 and July 1, 2019. A control rating of one to five was given to each tree plot; one meant there was no control and five meant there was full control.

The results of the study are shown in Figure 1. Water was the control and provided no control across evaluation dates. Paraquat provided good initial control, but this was short lived. Also, it provided better control with the latest treatment date. NAA provided better and longer lived sucker control, although the results were somewhat variable. Even by July 1 some controlsome control was still observedfrom the April 30 NAA treatment. UAN also provided better control with later treatment dates. The May 20 treatment still provided acceptable control by July 1. UAN produced the longest lasting control. In general, later treatments provided longer lasting control in the period we evaluated.

Based on this research, we can say that UAN is a good material for managing sucker fish from late spring to early summer. It provided better control than Paraquat and control equal to NAA. Paraquat, NAA and UAN are easy to apply with aboom sprayer in a commercial setting. Paraquat has the added advantage of also suppressing early weed growth. UAN has the added advantage of providing some nitrogen as well as suppressing early weed growth.

The estimated cost of sucker control productson a per-acre basis is shown in Table 2. The lowest cost product is Paraquat followed by UAN and NAA. The cost of application labor, fuel, and depreciation are not included in these costs. But using 20 gallons of UAN per treated acre gives about 20 pounds of nitrogen per planned acre, which cancels out the nitrogen that would be used otherwise.

Table 2. Cost per treated acre of various sucker control products on a projected area basis. This is based on a six-foot treated area per tree row (based on 2019 chemical prices).

In apple orchards, not all rootstocks are equally prone to sucker. We recommend avoiding planting apple trees on M. 7 rootstocks. Also, nursery trees can have less suckering if they are “high-budded” so the roots can be planted a little lower. However, this approach can be overdone. Avoiding mechanically damaging rootstocks can also prevent suckering.

The references to chemicals in this document are there to make things easier for you. They don’t mean that certain products are better than others that do the same thing. Plant growth regulators are classified as pesticides by the U. S. Environmental Protection Agency. You are responsible for using pesticides according to the manufacturer’s current label directions. Follow directions exactly to protect people and the environment from pesticide exposure. Failure to do so violates the law. You can use this information to learn about what materials are legal to use and what works for growers. No implication is intended that Utah State University recommends the use of any materials.

Xin Dai from the Utah Agricultural Experiment Station; Teryl Roper from the Department of Plants, Soils, and Climate at Utah State University; and Samuel Johnson, an MS student

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Many types of fruit trees produce suckers around the base of the tree. Crown suckers arise in the area immediately surrounding the tree trunk. Root suckers can arise from roots further away from the trunk. Insect pests like wooly apple aphid can live in suckers around trees, and diseases like fire blight can get in through them. If suckers are profuse they interfere with in-row weed management and can absorb systemic herbicides such as glyphosate. Some rootstocks used for fruit trees such as M. 7 for apples and Mazzard for cherries are genetically predisposed to produce suckers. M. 9 clone RN-29 is more inclined to sucker than other M. 9 clones. In some cases, sucker growth is a symptom of partial incompatibility between the rootstock and scion. Suckers can also result from injury to the crown such as extreme cold or mechanical injury. Whatever the cause, managing suckers takes time and expense.

Sucker management falls into two general categories: mechanical and chemical. Each approach has merit depending on the orchard situation.

When onlya few suckers are present, they are often removed during dormant pruning. In severe cases, sickle bar style mowers or gas-powered hedge shears have been used to remove suckers. But sometimes, when suckers are cut off mechanically, more than one new shoot can grow from a single sucker, which makes the problem worse. Mechanical control is also expensive and labor intensiveand may have to be done more than once per year. Related to mechanical control is control by heat. In a USU trial, burning suckers with a propane torch provided good control that lasted several weeks. This may be an effective approach for a few suckers here and there. To treat an entire block with a torch, the vehicle would have to move very slowly and use a lot of propane. Care would also need to be taken to not damage irrigation tubing.

Chemical control of suckerscan be effective andis less labor intensive than mechanical control. Many acres can be treated in a day by a single operator. Chemical controls for suckers can be grouped into three categories: Plant growth regulators, herbicides, and desiccants.

Commercial fruit growers have long used a synthetic auxin,Naphthalene Acetic Acid (NAA),to reduce the growth of suckers. It is the same plant growth regulator (PGR) that is used to thin fruit, but it is used at a different time and in a different amount. Because NAA will cause a thinning response, application must be delayed until a month after petal fall. This allows time forthe fruit to set and become less sensitive to NAA. Still, it should be applied with nozzles that make big droplets at a low pressure (10–20 psi) to keep it from drifting. A specific formulation of NAA (Tre-Hold A-112™)is registered for this use. For apples an 0. 5% to 1% solution of NAA should reduce the growth of root suckers.

Some specific contact herbicides are registered for sucker managementfor fruit trees. Even though these are registered to kill or stop sucker growth, they are still herbicides and can hurt trees, especially young trees whose bark is still green and not corky. Therefore, care must be taken during application to not treattree trunks. Young trees should have trunk wraps installed before application ofherbicide products. Contact herbicides are better than other types of herbicides because they can kill weeds that have come up since the spring applications.

When using herbicides to get rid of sucker plants, it’s best to spray them only when the wind is calm and with low pressure and big droplets. Low drift nozzles are preferred. The use of off-center nozzles may lead to overspray on trunks. For these contact herbicides, good coverage of the foliage is essential. Thus, sufficient water must be sprayed to thoroughly wet the leaves. Control is best when the suckers are still youngand succulent, and not woody.

Paraquat(Gramoxone™) is a caustic, non-systemic, post-emergent herbicide that burns green vegetation. Paraquat is quickly taken up by green plant cells and reacts with photosynthesis to make superoxides, which destroy plant cells. Paraquat is a restricted use pesticide that can only be mixed and used by certified pesticide applicators. It is very dangerous to humans. It provides good burn down of suckers at the higher rates.

Glufosinate (Rely280™, Cheetah™) is another contact herbicide that is registered for sucker management. It is the slowest acting of the herbicide products included in this fact sheet. It can take 20-25days to reach the level of control provided by the other herbicides in 10-14 days.

Carfentrazone-ethyl (Aim EC) is registered for sucker control in fruit trees. Aim must be applied using a hooded sprayer to minimize the opportunity for drift. Also, it must be mixed with an appropriate rate of a nonionic surfactant or crop oil concentrate. Aim works well to control suckers when they are green and not woody, but the risk of damage from drift makes it a less desirable option.

Pyraflufen-ethyl (Venue) is a contact herbicide for post-emergent control of a range of broadleaf weeds. It also has a supplemental label for control of suckers in fruit trees. It is fast acting and effective at the 4 fl. oz/a rate. Cherry suckers are more susceptibleto Venuethan apple.

Table 1. Use patterns for herbicides registered for sucker control in tree fruits. Check product labels for specific use information.

We just recently learned about a material that is used in other places to keep tree fruits and nuts from sprouting. Urea Ammonium Nitrate (UAN) is a liquid fertilizer that is a powerful desiccant. It is not registered as a pesticide. It can be purchased in co-op agronomy centersin the Intermountain West. When sprayed on suckers in the spring it desiccates the succulent foliage and stunts growth. Since it is 32% nitrogen, by weight, it also provides additional nitrogen when applied for sucker control.

We tested UAN against NAA, paraquat, and burning with either a propane torch or a water control in 2019. The trial was conducted on a block of ‘Gala’ on EMLA. 7 rootstocks at the Kaysville Research Farmin Kaysville, Utah. The trees were planted in 2006and had a long history of extensive root suckering. In the early spring we cut off all the existing suckers with hedge shears. That made sure that the suckers would grow back, and it made sure that none of the treatments had suckers when the trial started. Treatments were assigned to trees in five orchard rows in a completely randomized designwith four replications. Applications were made on four dates in 2019: April 30, May 3, May 9 and May 20. The first treatments were made when initial sucker growth ranged between three and six inches. Treatments were Water, 1% NAA, Paraquat, UAN, and burning with a propane torch. NAA and Paraquat were mixed immediately prior to use. All liquid treatments were applied with a one-gallon pump up sprayer and the suckers were sprayed to runoff. Our propane torch burned the area under the tree until none of the suckers had any leaves on them.

We evaluated the treatments on May 9, June 10 and July 1, 2019. A control rating of one to five was given to each tree plot; one meant there was no control and five meant there was full control.

The results of the study are shown in Figure 1. Water was the control and provided no control across evaluation dates. Paraquat provided good initial control, but this was short lived. Also, it provided better control with the latest treatment date. NAA provided better and longer lived sucker control, although the results were somewhat variable. Even by July 1 some controlsome control was still observedfrom the April 30 NAA treatment. UAN also provided better control with later treatment dates. The May 20 treatment still provided acceptable control by July 1. UAN produced the longest lasting control. In general, later treatments provided longer lasting control in the period we evaluated.

Based on this research, we can say that UAN is a good material for managing sucker fish from late spring to early summer. It provided better control than Paraquat and control equal to NAA. Paraquat, NAA and UAN are easy to apply with aboom sprayer in a commercial setting. Paraquat has the added advantage of also suppressing early weed growth. UAN has the added advantage of providing some nitrogen as well as suppressing early weed growth.

The estimated cost of sucker control productson a per-acre basis is shown in Table 2. The lowest cost product is Paraquat followed by UAN and NAA. The cost of application labor, fuel, and depreciation are not included in these costs. But using 20 gallons of UAN per treated acre gives about 20 pounds of nitrogen per planned acre, which cancels out the nitrogen that would be used otherwise.

Table 2. Cost per treated acre of various sucker control products on a projected area basis. This is based on a six-foot treated area per tree row (based on 2019 chemical prices).

In apple orchards, not all rootstocks are equally prone to sucker. We recommend avoiding planting apple trees on M. 7 rootstocks. Also, nursery trees can have less suckering if they are “high-budded” so the roots can be planted a little lower. However, this approach can be overdone. Avoiding mechanically damaging rootstocks can also prevent suckering.

The references to chemicals in this document are there to make things easier for you. They don’t mean that certain products are better than others that do the same thing. Plant growth regulators are classified as pesticides by the U. S. Environmental Protection Agency. You are responsible for using pesticides according to the manufacturer’s current label directions. Follow directions exactly to protect people and the environment from pesticide exposure. Failure to do so violates the law. You can use this information to learn about what materials are legal to use and what works for growers. No implication is intended that Utah State University recommends the use of any materials.

• Johnson, S. L. 2020. Opportunities for Optimal Apple Production Management in Arid Conditions. Utah State University. MS Thesis. Smith, T. J. and E Gutierrez. 2014.
• Studying how Venue, Gramoxone, Aim, and Rely herbicides work to get rid of root and crown suckers in apple and cherry trees Massachusetts Fruit Notes 79:1-4. Tukey, R. B.
• T. J. Raese. 1995. Chemical control of water sprouts and suckers. Washington State University, Extension Bulletin EB1593.

Xin Dai from the Utah Agricultural Experiment Station; Teryl Roper from the Department of Plants, Soils, and Climate at Utah State University; and Samuel Johnson, an MS student

What to do About Suckers at Base of Trees

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