NC State Extension Publications

Problem

Herbicide injury caused from cellulose-inhibiting herbicides such as indaziflam and isoxaben.

Symptoms

  • Abnormal root and shoot tips.
  • Mottled, puckered, chlorotic foliage and growing points.
  • Roots may be swollen or have encircling necrotic bands just behind the root tips.
  • Susceptable seedlings often do not emerge from the soil.
  • Indaziflam may cause soil line girdling with occasional stem swelling just above the girdle on susceptible plants.
  • Girdled stems often result in wilting followed by browning of entire above-ground portion.
necrotic growing point, "puckered" and yellowed foliage

Isoxaben injury to Hydrangea. Non-treated on left.

J. Neal  CC BY-NC-SA - 4.0

Knockout rose tender young foliage is damaged

Knockout rose tender young foliage is damaged by over the top spray application of indaziflam. Note the “puckered” foliage as well as tip necrosis. Photo two weeks after treatment.

J. Neal  CC BY-NC-SA - 4.0

Knockout rose foliage injured by over the top spray application

Knockout rose foliage injured by over the top spray application of indaziflam. Photo two weeks after treatment.

J. Neal  CC BY-NC-SA - 4.0

Isoxaben injury to hydrangea foliage. Older leaves unaffected.

Isoxaben injury to hydrangea foliage. Note older leaves are unaffected.

J. Neal  CC BY-NC-SA - 4.0

Isoxaben injury to hydrangea.

Isoxaben injury to hydrangea. Tip necrosis forms within two weeks of over the top application.

J. Neal  CC BY-NC-SA - 4.0

Normal foliage of non-treated hydrangea.

Normal foliage of non-treated hydrangea.

J. Neal  CC BY-NC-SA - 4.0

Red maple stem – normal stem growth.

Red maple stem – normal stem growth.

 CC BY-NC-SA - 4.0

Red maple stem girdling caused by an overdose of indaziflam.

Red maple stem girdling caused by an overdose of indaziflam.

 CC BY-NC-SA - 4.0

Stem girdling by indaziflam over-dosing results in sudden death.

Stem girdling by indaziflam over-dosing results in sudden death of above-ground tissues, usually in hot weather. Non-treated on left, treated on right.

J. Neal  CC BY-NC-SA - 4.0

Blackened growing point and misshappen leaves on lantana

Isoxaben injury to lantana -- 2 weeks after treatment.

J. Neal  CC BY-NC-SA - 4.0

upward cupping foliage, stunted, yellow and mishaped new growth

isoxaben + prodiamine injury to rudbeckia.

J. Neal  CC BY-NC-SA - 4.0

Plant Entry and Symptom Expression

Cellulose inhibitors may affect both roots and shoots. Herbicides with this mode of action are usually applied prior to weed emergence but may cause injury to emerged and established plants by foliar absorption, inhibition of root growth, or stem girdling at or just above soil line. Roots and/or tender new shoots are injured within a few days following application. Soil movement is minimal and volatilization and photodegradation are not a concern.

Similar Problems

Cellulose and cell wall inhibitor injury may be confused with symptoms from:

  • Stubby roots caused by dinitroanaline herbicides such as oryzalin, pendimethalin, prodiamine, trifluralin.
  • The reduced root size and number caused by the mitotic inhibitor dithiopyr, a pthalic acid.
  • Puckered, curled and mottled foliage may be confused with damage from dinitroanaline.
  • Herbicides or sucking insects (such as aphids).
  • Mottled foliage may sometimes be confused with nematode, plant virus and/or nutritional disorders.

Herbicide Mode of Action Category

WSSA – 21
HRAC – L

Authors

Professor of Weed Science, Extension Specialist & Department Extension Leader
Horticultural Science
Professor Emeritus
Cobleskill Univ.
Assistant Professor
Horticultural Science
Extension Associate, Horticulture
Horticultural Science

Publication date: Dec. 11, 2015

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.