SE Asia

Malaysian agriculture has had a wake-up call to the threat posed by herbicide resistant weeds. Paraquat has an essential role to play in avoiding this potentially huge problem. A report by the Paraquat Information Center of the discovery of populations the noxious weed goosegrass (Eleusine indica) resistant to the non-selective herbicide glufosinate has now been confirmed by publication in a scientific journal¹.
A vegetable farmer in Malacca state and planters at an oil palm nursery in Pahang state had suspected that glufosinate was failing to control goosegrass. Subsequent investigations have now confirmed that one population shows a two-fold resistance and the other an eight-fold resistance.
These are the first cases of weed resistance to glufosinate to be recorded anywhere in the world after more than 25 years of use. This is reminiscent of the fall of glyphosate to the first resistant weeds in the mid 1990’s. Escalating use of glyphosate over a similar period ultimately resulted in resistance. The second weed species to have confirmed glyphosate resistance was also goosegrass in Malaysia².

“Time and tide wait for no man”, so they say. Rice farmers living in coastal areas of South Sumatra, and Central and East Kalimantan in Indonesia know this only too well. Their paddy fields are flooded by river water pushed back up the deltas by each incoming tide. Preparing the land is especially difficult. Not only do weeds grow incredibly vigorously under the swampy conditions, but plowing the land too deeply can result in crop failure. Although the high organic matter topsoil is fertile, below lies a yellow layer of toxic iron pyrite. This is phytotoxic to the rice if disturbed.
Farm labor is often difficult to find. Working in hot weather and high humidity in these tidal-swampy areas makes land preparation a time consuming and exhausting job. Traditionally, farmers slash the tall weeds with a long machete called a “tajak”. Weeds have been controlled this way for hundreds of years by tidal rice farmers. The cut weeds are collected and piled-up in heaps called “puntalan” and left to dry under the sun. The puntalans have to be turned frequently to assist drying and encourage decomposition of the biomass. When dry, farmers spread the remains of the vegetation evenly over the flooded paddies. After plowing, rice seedlings are transplanted a couple of weeks later.

In the Philippines, more successful results from a project using paraquat to control weeds and prevent soil erosion have been announced. Since 2005, researchers from several universities and other organisations have been collaborating to study approaches to reducing the serious threat posed by soil erosion to food production and the environment.
Professor Gil Magsino from the University of the Philippines presented the results and conclusions from the Sagip-Lupa project’s 4th Annual Report at the University of Benguet recently.
Prof. Magsino noted that an annual loss of 2 – 4 cm of topsoil from fields in the Philippines has become commonplace, but with the imperative of achieving sufficient levels of food production this cannot be sustained.

Benefits of paraquat-based agronomy

Less soil lost
Higher yields
Lower input costs
Time savings

Plants and soil organic matter are key to reducing soil erosion. Living or dead mulches of plants covering the soil resist the impact of rain, and roots and organic matter bind soil particles together. Traditional methods of weed control such as hand hoeing and plowing remove unwanted plant material, ie weeds, and disturb the soil, encouraging erosion.
However, using an agronomy system based on paraquat means that weeds are only removed when necessary to protect yields.

In Asia alone, more than two billion people obtain over 60% of their calories from rice. It is the most rapidly growing source of food in Africa and is critical to food security. Long grain rices are typically of the indica race and include the fragrant Jasmine rice from Thailand and Basmati rice from India. Short grain rice, typically japonica, is usually more sticky than long grain and is favoured in Japan. Saki rice is grown in Japan to make rice wine, and in Indonesia there are red and black grained varieties. About 80% of the world's rice is grown by smallholders in these places. In Asia, women are often responsible for rice farming as men have moved to work in the cities.
Efficient and productive rice-based production systems are essential for economic development and for improved quality of life for much of the world's population. Plant breeding, crop protection, water management and fertilization have increased productivity and reduced the costs of production.
Weeds can reduce the yield and quality of rice by competing with the crop for light, nutrients and space; and their seeds can contaminate the harvested grain. Some of the most widespread and aggressive weeds are the Echinochloa species (barnyardgrass). Infestations of only ten of these weeds per square metre have been recorded to reduce yields by 25%.