ISSUE #553

553 - Weeds and Rhizoctonia: "Don't Get Behind"


Late planting of the 2011 crop presents a different set of challenges from the early planted 2010 crop with much warmer seedbeds.

WEEDS: Soils usually warm up faster with late planting with weed and beet seedlings emerging together. When this occurs weeds compete more vigorously with beets and risk of yield loss is greater. Timing that first herbicide application is more critical than ever.

DISEASES: Increased likelihood of warm soils during germination and emergence increase risk of stand loss and decreased yield from Pythium, Aphanomyces and Rhizoctonia. At plant applications of Quadris and Headline or POST emergence applications of Quadris and Proline will need to be made within 3-4 weeks of emergence.

Weed Control With Conventional Herbicides

553Before Planting Strategies:

  • Use high plant populations for best competition
  • Maximize weed control with pre-plant tillage
  • Use starter fertilizer to enhance crop competition

Soil Applied Herbicide

  • Nortron applied PPI or PRE will maximize weed control
  • Use highest labeled Nortron rates for your soil type
  • PPI Fargo will maximize resistant wild oat control
  • Strongly consider a preemerge glyphosate application

Soil Applied Herbicide Benefits

  • Reduces early weed competition
  • Usually reduces POST applications
  • Improves POST application activity
  • Weather insurance for POST timing problems

Microrate Mixing Order

  • Fill tank 1/3 full of water and adjust pH to 8-9 with correct adjuvants
  • Slurry Upbeet in warm water and add to tank
  • Fill the tank 2/3 full of water
  • Add Nortron if using it
  • Add Betamix or Progress
  • Add Stinger and grass herbicide
  • Fill tank with water and add the remaining MSO or basic blend

Microrate Use Strategies

  • Apply the first application to cotyledon weeds
  • Repeat applications every 5-7 days
  • Increase Betamix or Progress rates as needed after the first application
  • Always include Betamix or Progress, Upbeet, Stinger and a grass herbicide as needed
  • Add 3-4 oz. of Nortron to the microrate to maximize activity
  • Call the aerial applicator if necessary to stay on schedule

Rhizoctonia Control Strategies

  • Apply Quadris or Proline at the 4-6 leaf stage - see Table 1.
  • Monitor soil temperatures with the Text Message Alert System
  • Apply fungicide by the time soil temperature reaches about 65°F
  • It's better to apply fungicide too early versus too late
  • Don't apply POST fungicides to bare soil, cotyledon, or 2l-leaf beets

Table 1: Efficacy of band-applied fungicides applied at the 6 to 8-leaf stage and then inoculated with Rhizoctonia solani for control of crown and root rot and sugarbeet yield and quality compared to two controls (non-inoculated, no fungicide and inoculated, no fungicide). Windels and Brantner, UM NWROC, 2010

Table 1

Treatment and Rate (7-inch band)No. Harv. Root/100 ftzRCRR (0-7)zYield T/AzSucrosezRevenue ($/A)z
%Lb./tonLb. Recov./A
Non-inoculated control 142 2.8 23.8 16.8 311 7537 1011
Rhizoctonia inoculated No fungicide control 73 5.7 9.5 15.6 286 2780 342
Quadris @ 14.3 oz.acre 162 1.5 24.5 18.0 338 8295 1184
Headline @ 12 oz./acre 147 2.6 23.7 16.6 308 7228 831
Proline @ 5.7 fl oz./A 160 1.6 24.7 17.5 327 8064 1115
LSD (P=0.05) 30.5 1.1 5.3 1.1 23.7 1693 247

Starter Fertilizer

Don't neglect using a starter fertilizer. Be sure it contains adequate amounts of phosphorus.

Mechanical Control

Don't neglect use of the row crop cultivator and rotary hoe when necessary.