WEED MANAGEMENT PROGRAM

NARC, Islamabad

INTRODUCTION

Weeds are one of the dominant elements of the pest complex of major crops in Pakistan. Yield losses due to weeds are the result of weed competition for light, water, nutrients and allelopathic effects. In Pakistan losses caused by weeds, on the average in the different crops have been assessed over the year by the Weed Management Programme. In terms of economic losses this amounts to millions of rupees annually. Estimated losses observed in field trials range from 10-75 percent in different crops.

The research results clearly indicate that for agricultural uplift effective weed management is a major component. Weed management practices mostly depend on manual and simple mechanical measures. In response to high labor costs and the increasing availability of herbicides in the market, the use of herbicides by progressive farmers has increased. This increase will lead to several problems including herbicide resistance, a problem that requires immediate attention. Weed problems is agro-ecosystems result not only from enormous numbers of propagules, but lack of uniformity in their germination.

The distribution patter of a weed is one of the major factors leading to its noxiousness and in developing control strategies. Its presence in the different agro-ecological zones and the crops have to be documented. Information most needed for successful future control of weeds is knowledge of rate and pattern of alien weed spread. An important example for Pakistan is Parthenium hysterophorus.
 

Research in Pakistan to determine the inter-specific yield losses in the major cropping systems, i.e. rice-wheat and cotton-wheat has been initiated during the various phases of the programme. Determining these yield losses is essential for the implementation of an integrated weed management system at the present time.

There has been a rapid change in the weed flora. During the eighties Phalaris minor emerged in short stature wheat, Trianthema portulacastrum in cotton and Galium as a resistant weed in wheat. Avena fatua, Phalaris minor and Cirsium arvense are the major problem in wheat with Bromus emerging as the biggest challenge in the highly productive wheat growing areas of the country. Rumex dentatus and Cnicus benedictus are a challenge during rabi. Sorghum halepense and Cyperus rotundus are prevalent in cotton where broad leaf leaf weeds have been controlled. Sphenochlea zeylenica is spreading in rice in lower Punjab and Sindh. Changes in species composition in agriculture lands must also be evaluated to alert scientists and farmers to the invasion of new weed species.

The Pakistan Weed Science Society was established in 1987 after the Pak Indo US Weed Control Workshop held at the National Agricultural Research Centre, Islamabad. The first volume of Pakistan Journal of Weed Science Research was published in 1988 by the Pakistan Weed Science Society established at National Agricultural Research Centre with the efforts of the scientists working at the Weed Science Institute at the time.

The mandate of the weed science program is to conduct basic and applied research on biology, ecology and integrated management of weeds in crops of economic importance in collaboration with the commodity programs of NARC and provincial institutes.

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