Shortstop 2SC Over-Regulation Protocol

We are starting to see Shortstop® 2SC being used for many of the secondary effects. When Shortstop 2SC is applied, not only will above ground growth be regulated, but we also see thicker leaves, waxier leaves, increased fibrous roots, and healthier looking plants. With these secondary effects, we are observing trees with less leaf scorch due to drought, less damage after construction, and an increase in disease suppression.

Shortstop 2SC has 9 categories for treating trees (more if you include shrubs). It is important to follow the label and treatment guidelines, as each species of plant will have varying levels of sensitivity to the active ingredient (Paclobutrazol). There are other factors that also need to be accounted for when treating. For instance, the applicator can reduce the rate based on pre-existing conditions with the tree or environment.

It is not uncommon for folks to accidentally over apply the Shortstop 2SC product. This can happen, even if you follow the Arborjet Recommended Treatment Rate Chart. Sometimes there are details that are overlooked, and sometimes there are conditions beyond our control. Either way, be sure to follow the below instructions to help the plant recover and reduce the chances of this happening again.

Symptoms of Over-Regulation:

The plant may have atypically small and distorted leaves. Small flowers and delayed blooming and leaf-out may occur. Shortstop 2SC typically does not kill trees or shrubs, but at high rates will kill grass (If you notice white/dead turf, remove it, along with the soil).

Over-regulation on a Japanese Maple

Management: Over-Regulated Trees and Shrubs

  1. Immediately remove the soil that was treated with Shortstop 2SC. This will reduce additional uptake of the active ingredient into the tree or shrub.
  2. Replace with organic matter and new soil – this will help absorb any additional product.
  3. For trees, consider a trunk injection with PHOSPHO-jet™. This will trigger the plant’s natural defense and encourage strong cell walls. It will also improve new stem, root, and leaf growth. The plant should recover by the next growing season.
  4. For trees and shrubs, consider a soil application of a fertilizer/soil conditioner containing nutrients, seaweed extract, humic acid and humectants. We suggest NutriRoot® for optimum results and to encourage plant and soil health.