Castor

Weed Management

Introduction

  • In Castor, weed problem is most intricate because of its tall habit and hence hardly in smothering effect.
  • Castor is highly susceptible to weed competition in the early stages, viz., upto 45-60 days from sowing depending on the variety.
  • Besides, the weeds also serve as collateral or alternate hosts to jassids and white flies.
  • The main weeds observed are, 1. Digitaria 2. Echinochloa 3. Celosia 4. Cleome 5. Cyprus 6. Cynodon 7. Eleusine 8. Convolvulus sp.

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Cultural control

  • In rainfed areas 2 or 3 intercultures with the help of bullock drawn blade harrows starting from 25-30 days after planting combined with one manual intra row weeding if necessary around plants or within the row after first interculture effectively check weed growth.
  • Square planting as adopted in certain pockets of Telangana help to run a blade harrow in both the directions and aid in effective weed control apart from creating a soil mulch.
  • Weeds are a more serious problem even in irrigated castor.
  • Hence, the crop may need 2 or 3 hand weedings at intervals of 15-20 days in order to keep weeds under check.
  • When the crop is 35-45 days old, open 45-60 cm wide and 30-45 cm deep furrows in between rows by running broad band iron plough.
  • Such practice not only provides earthing up to the young plants but also facilitates easy irrigation through furrows, with minimal or no direct contact of above ground portion of plants with water.

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Chemical Control

    1.  Alachlor 1.75 kg/hac or CDAA at 6kg/hac as pre-emergence or      EPTC at 2kg/hac as pre planting application is advocated.
    2.  Fluchloralin or Trifluraline (a) 1kg ai/hac as pre plant application is      effective.

Chemicals Used In Weed Control

EPTC:

(Eptam) EC = 75% Gr 10%

  • Eptam is a selective, pre-planting herbicide which is mechanically incorporated into the soil to a depth of 5-7cm immediately after application to avoid volatile losses.
  • The weeds controlled are nut sedge (cyprus sp) perennial grasses such as johnson grass (sorghum halepense), barnyard grass (echinochloa crusgalli), quark grass (Agropyron repens), Ipomea sp, lambs quarter (Chenopodium sp) purslane (portulaca Oleracea), solanum sp, pig weed (Amaranthus sp) etc.
  • It acts on germinating seeds and hence applied just before the seedlings are established.
  • It is absorbed by roots and translocated to the leaves and epidermal shoots.
  • It inhibits growth in the meristematic region, cell division, cell elongation and expansion of plumules of germinating seedlings.
  • It is absorbed into dry soil but readily lost from the soil by volatilization when the soil surface is wet at the time of application.
  • It is readily lost by metabolization and hence does not persist in dry soils for a longer period, 12-16 weeks. The rate applied is 2 to 4 kg/hac.

Fluchloralin

  • It is pre plant incorporated herbicide. It is orange, yellow Crystalline solid. Melting point is 42-43oC.
  • Its toxicity is acute oral LD 50 (rat) 1500mg/kg low order of toxicity to wild fowl.Toxic to fish.
  • It controls wide range of grasses and certain broad leaf weeds in castor.
  • Pre emergence application of Alachlor or Nitrofen or Pendimethaline at 1.25 kg a.i/ha is equally effective under irrigation.

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Telangana

Castor

Castor Management