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Ask the Experts

Our experts answer the following questions regarding TGR applications.

Which is a better application technique, backpack or tank?
Do you have solutions to the more common problems found out in the field while doing TGR application?
When is not a good time to apply TGR's?

Backpack versus Tank Applications:

Backpacks have a place in applications for low volume herbicides and some types of foliar treatments, but not in regards to tree growth regulator applications on a production basis. Backpacks are cumbersome, heavy (40+ lbs. with liquid), and hard on the applicator’s body.
Soil injection applications for TGRs require approximately 90-120 psi and need the pressure to be consistent so the paclobutrazol can be spread sub-soil across the root system. Even if the backpack’s pressure gauge shows 110 psi, more than 50% of the pressure is lost immediately after the trigger is pulled.
If the applicator needs to do just 2 or 3 small trees, choosing soil injections with a backpack instead of basal drench would still make the application easier and faster. Just make more injection holes to compensate for the low pressure to ensure the ShortStop will spread completely & evenly throughout the root system.
Backpacks hold 2.5-3 gallons of RTU mixture that is equivalent to approximately 9500mLs to 12,000mLs. That amount of RTU mixture will treat about four medium-sized trees before the applicator will have to return to refill the backpack and treat more trees. If the applicator wants to work as efficiently as possible, using a 25+ gallon tank with agitation and consistent pressure makes more sense for most soil applications, especially tree growth regulators. Adding a 40-60’ hose extending from the tank would facilitate getting to the hard-to-reach locations. Click here to see our solution to this equipment issue. 

Problem Solving:

Be careful when applying TGRs around mulch, the product must reach beyond the mulch layer and beyond any plastic sheeting or other barrier. It is important to reach approximately 6 inches down into the soil/root mass, to effectively apply the ShortStop. During the application; move mulch or other “barriers” away from the base of the tree, make the application and then return the material around the tree.
When perennials are growing close to the base of the tree that is to be treated, the applicator has three choices of how to apply the TGR; apply at a “safe distance” from the plants, move the plants during application, or do not apply. If the application is a basal drench, the minimum distance from the outside of the trench to the plant(s) is 2-3 inches and if it is a soil injection, the minimum distance from the application site to the plant(s) is 8 inches. If the roots of the perennials are too entwined within the application zone, the perennial needs to be removed during the treatment. Once the RTU mix has been completely absorbed into the soil, then the perennial can be re-planted. If none of these options can be safely utilized then the third choice should dictate – do not apply.
When applying TGRs near a well-head, be sure to stay a minimum of 8-10 feet away from the well-head. Although ShortStop TGR does not move much in the soil from the application site, it is safer to keep this rule of thumb.
Because paclobutrazol has not been approved by the FDA, fruit & nuts that “set” during the growing season following an application should not be consumed. The amount of product that is found in the seeds is miniscule (parts per billion). The fruits and nuts can be consumed legally any other time.
If the area around the base of the tree is obstructed in some way (i.e.: sidewalk, driveway, retaining wall, etc.), it is still important to evenly apply ShortStop to the best of the applicator’s ability. An example of how to adjust the application to accommodate an obstruction, such as a sidewalk that runs alongside a tree, is to make injections or trench around as much of the base as possible. When the applicator reaches the sidewalk, run the injections or trench along it and across on the other side. Do not change the amount of volume recommended.
It can be complicated to calculate the volume for an application of TGRs on trees having multiple branches significantly below breast height with a single trunk or “group trees” such as birches. Instructions can be found on our TGR Rate Slide Chart. Click here to see our TGR Rate Slide Chart.
Some problems such as chlorosis, over-regulation and excessive crown damage, need additional information to suggest solutions, please call our office at #269-663-7467 for assistance.

When NOT to apply TGRs:

Situations when the applicator should not apply ShortStop TGR are when the ground is very wet (super-saturated), when the ground is frozen, and when the tree appears very stressed.
When a stressed tree has 40% or more of the crown missing or dying, do not treat it with TGRs. The tree already has an excessive amount of abscissic acid due to the original stress; applying paclobutrazol ultimately increases the amount of the abscissic acid to a level that may be detrimental to the tree.

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