The role of cultural practices in weed control under current agricultural concepts

Abstract

The future of weed control in arable crops needs new strategies based on increased precision with respect to three major aspects of weed management: 1. prevention - reduction in weed effects through adapted crop management; 2. direct weed control - improvement in technology with respect to herbicide application and efficacy; 3. decision-making - improved information technology with respect to weed management. The first component (prevention) involves any aspect of management that favours the crop relative to the weeds. The second component (control) deals with the development/improvement of weed control methods and is strongly related to precision technology. Four approaches to weed control can be distinguished: mechanical, physical, biological and chemical. In mechanical control, many developments are taking place. Tillage and cultivation are generally becoming more important for weed suppression. Soil fertility is a key component of all farming systems managed with the goal of sustaining or improving yields, and fertilization with synthetic or organic nutrient sources is standard practice in conventional farming systems. Cover crops can suppress weed establishment and growth, thence the number of weeds and vegetative propagules infesting succeeding crops. Intercrops can in many cases reduce weed density and growth more effectively than sole crops. For biological weed control, the challenges are the effective application and stimulation of epidemics of pathogens in the crop that are both effective and selective. Combinations with critical period approaches may be useful, as pathogens do not always kill the weeds. Today, the number of new herbicides being introduced has decreased and integrated weed management has become the guiding concept. Development of the IWMS (Integrated Weed Management Systems) has to include selection, integration and implementation of new technologies on the basis of their anticipated economic, ecological and sociological consequences. Costs, benefits and risks must be carefully examined before final decisions can be made. Organic farming is facing big challenges in the field of fertilization / nutrition and plant protection, since the application of chemicals (fertilizers and pesticides) have been rejected generally. Weed management strategy in organic agriculture should be based both on preventive and direct control methods, which include mainly those with mechanical, biological and physical nature of actions.

Kontrola korova, bolesti i štetočina, je izuzetno važan segment konvencionalnog negovanja useva u biljnoj proizvodnji, posebno osetljiv u savremenim LISA (Low-input Sustainable Agriculture) - ekološkim sistemima zemljoradnje (Organic Farming), koji isključuju gotovo u potpunosti hemijske mere borbe. Smatra se da će budućnost istraživanja i zauzimanje novih strategija u primeni novih mera u borbi protiv korova u praksi biti i dalje vrlo aktuelno i zasnovano na jasnijem određenju važnih činilaca bez kojih se ne može zamisliti borba protiv korova, a to su: 1. Prevencija (smanjenja zakorovljenosti primenom brojnih preventivnih mera); 2. Direktne agrotehničke mere; 3. Uvođenje informacionih tehnologija. Preventivne mere borbe protiv korova su vrlo važan činilac u efikasnoj zaštiti od korova u svim sistemima zemljoradnje. Posebno su značajne u borbi protiv korova posmatrano na duže staze. U preventivne mere borbe protiv korova spadaju sve one mere koje imaju za cilj zaštitu njivske površine od zakorovljavanja, dakle, svi oni slučajevi koji sprečavaju dolazak semena korova i njihovih vegetativnih organa na njivu. Od direktnih agrotehničkih mera koje se koriste u kontroli korovske vegetacije najveći značaj imaju svi načini i sistemi obrade zemljišta, đubrenje, setva, mere nege, a posebno sistemi biljne proizvodnje gde veliki značaj ima plodored. Dosadašnja strategija i praksa u suzbijanju korova u konvencionalnim sistemima zemljoradnje trpi brojne promene. Savremeni sistemi zemljoradnje preko integralnih sve više računaju na ekološke postulate koji su najprisutniji u organskoj proizvodnji kao još uvek jednom alternativnom pravcu. Delimično ili potpuno odsustvo primene agrohemikalija (mineralnih đubriva i pesticida) zahteva potpuno drugi pristup u borbi protiv korova. Agrotehničke mere moraju se adaptirati i uvesti u nove tehnologije gajenja, pri čemu će izuzetan značaj dobiti plodored kao srce ovih sistema.