Commercial Disease Controls
The Pennsylvania State University
Cooperative Extension
Carrots
Seed Treatment
Use seed treated with Maxim 4FS (0.08-0.16 fl oz/100 lb seed) for Rhizoctonia and Fusarium control and Apron XL LS (0.16-0.64 fl oz/100 lb seed) for Pythium control.
Disease Control
Damping-Off (Pythium and Phytophthora)
Apply the following preplant incorporated or as a soil-surface spray after planting.
mefenoxam--1-2 pt Ridomil Gold 4E/Aor 2-4 pt Ultra Flourish 2E/A
Aster Yellows
Use insecticides to control leafhoppers, and keep weed populations down on periphery of field early in the season to prevent transmission by leafhoppers from the weeds into the crop.
Leaf Blights (Alternaria and Cercospora)
Several varieties such as Bolero, Calgary, Carson, Cheyenne, and Choctaw exhibit tolerance to leaf blight and should be grown where adapted. For susceptible varieties, begin applications when disease threatens or early July and continue every 7 to 10 days until frost. Do not make more than three sequential applications of Cabrio or Quadris before alternating to chlorothalonil. Under severe defoliation, add urea (10 pounds per acre) to encourage new leaf growth.
azoxystrobin (Quadris--9.2 - 15.4 oz 2.08F/A or Amistar--3-5 oz 80WDG/A, or
Cabrio--8-12 oz 20EG/A, or
chlorothalonil (Bravo, Echo, Equus)--l.5-2 pt 6F/A or OLF, or
Endura--4.5 oz 70W/A, or
Pristine--8-10.5 oz 38WG/A, or
Rovral (Alteniaria only)--1-2 lb 5OWP/A, or
Switch--11-14 oz 62.5WG/A (Alternaria only)
White Mold
The following biological fungicide has been tested in some states; however, limited information is available on effectiveness in the mid-Atlantic region. Apply 3 to 4 months prior to the onset of disease to allow the active agent to reduce inoculum levels of sclerotia in the soil. Following application, incorporate to a depth of 1 to 2 inches but do not plow before seeding cole crops to avoid untreated sclerotia in lower soil layers from infesting the upper soil layer.
Contans--2-4 lb 5.3WG/A
Storage Rots (Botrytis, Sclerotinia)
Remove all damaged roots before placing in storage. Remove roots from field and place in storage at 32 degrees F (O degrees C) and 90 to 95 percent relative humidity immediately after digging. As carrots are going into storage, dip into the following fungicide solution for 10 seconds.
Mertect 34OF--42 fl oz/100 gal
Note: Where trade names are used, no discrimination is intended
and no endorsement by the Cooperative Extension Service is implied.
Information provided is intended for consideration by the user, but is not
intended to be a recommendation. Production decisions should be based on
consideration of many types of information (scientific, experiential, economic,
legal, etc.) available to the user.
