Efficient weed con­trol re­quires close at­ten­tion to de­tail at ev­ery stage

Irish Independent - Farming - - Front Page -

con­trol ( see ta­ble 1, be­low). A grower can re­duce the ef­fect the prod­uct has on the sus­cep­ti­ble weeds by ei­ther re­duc­ing the dose rate or ap­ply­ing onto a very large weed. In ad­di­tion, poorly ap­plied prod­uct, com­pli­cated tank mixes and re­sis­tance, as is com­mon with corn marigold and chickweed to ALS her­bi­cides, are all is­sues that will com­pro­mise the ef­fi­cacy of the prod­uct.

The wa­ter: Where wa­ter qual­ity is sus­pected, then the ad­di­tion of ad­ju­vant (non-ionic wet­ters) agents can help.

The sprayer: Un­even ap­pli­ca­tion as a re­sult of worn or blocked noz­zles can re­sult in poor weed con­trol, es­pe­cially if con­di­tions are not ideal. Noz­zle se­lec­tion can also ef­fect the even­tual out­come. Gen­er­ally, as stan­dard, sprayers are fit­ted with a 025-04 flat-fan noz­zle. The cal­i­bra­tion of the sprayer us­ing these noz­zles is vi­tal to en­sure the her­bi­cide is ap­plied at the cor­rect wa­ter vol­ume and spray qual­ity.

The weeds: Cor­rect iden­ti­fi­ca­tion of size and type of tar­get weeds in a field is es­sen­tial. Gen­er­ally, weed con­trol in spring ce­re­als should be com­pleted by early tiller­ing stage of the crop. At this stage, weeds will not have passed the two true-leaf stage.

If good grow­ing con­di­tions pre­vail for three days be­fore ap­pli­ca­tion, rates of her­bi­cides can be dra­mat­i­cally re­duced. Re­sis­tant chickweed is eas­ily con­trolled with the ad­di­tion of CMPP or Flurox­ypyr. Con­trol of re­sis­tant marigold is more dif­fi­cult with the ad­di­tion of Galaxy or a HBN such as Stel­lox.

The weather: Grow­ing con­di­tions be­fore ap­pli­ca­tion of a her­bi­cide are more cru­cial than af­ter the her­bi­cide has been ap­plied. Dur­ing a cold spell, growth slows and plants build their de­fences, which in a plant's case is a build-up of a waxy layer on the leaf’s sur­face.

Dur­ing a rapid phase of growth, plant leaves ex­pand, new growth de­vel­ops and the waxy layer nar­rows. The waxy layer is the im­por­tant el­e­ment here. Her­bi­cides land­ing on a weed have to pass the waxy layer be­fore en­ter­ing the plant. The thicker the waxy layer the less her­bi­cide will en­ter the plant. There­fore, higher rates are needed to kill the weed or, as with the past cou­ple of sea­sons, poorer con­trol re­sults.

The crop: Crop den­sity plays an im­por­tant part in weed con­trol in win­ter and spring crops. A dense canopy shades the ground be­neath and starves the emerg­ing weed of wa­ter and nu­tri­ents, there­fore suf­fo­cat­ing the weed so that it will not de­velop to a ma­ture plant.

Newspapers in English

Newspapers from Ireland

© PressReader. All rights reserved.