Angry Italian Women Replaced by Herbicides


Le Mondine of the 1950s                                                                      Riso Amaro “Bitter Rice”

In Italian rice fields in the 1950s prior to the development of herbicides, weeding was done by hand. In May, the rice fields had to be weeded to prevent the young rice from being choked by other vegetation. Hundreds of women known as le mondine, or weeders, arrived from all parts of Italy to perform the delicate task of rooting out the weeds while leaving the young rice plants in place. Le mondine have become a nostalgic memory, immortalized by the famous film Riso Amaro or ‘Bitter Rice.’ It was a hard life for le mondine. They had to work bent double, up to their knees in water under a blazing sun. As the women weeded, they sang. One of the songs, Bella Ciao, was adopted by the Italian Communist Party to express the social injustice of the system. In the 1960s, most of the women left the rice fields when jobs opened up in cities, such as Milan, Genoa, and Turin. Today, herbicides are used in Italian rice fields.

“Italy is the largest rice producer in Europe, with about 235,000 ha in 2012. The main rice cultivation area is concentrated in the north-western regions of Piedmont and Lombardy where the continuous paddy rice system is widespread. Weed management is one of the key aspects of rice cultivation because pedo-climatic conditions are favourable to weeds that are generally competitive, there is a rich and persistant seed bank, and the weed flora is often dominated by difficult-to-control species… Consequently, farmers need to apply complex chemical and agronomic strategies to guarantee good weed control. Herbicide use is intense, with an average treatment frequency index higher than 2.5.”

Authors: Scarabel, L, et al.
Affiliations: National Research Council, Italy.
Title: Resistance evolution and sustainability of the rice cropping system: the Italian case study.
Source: Global Herbicide Resistance Challenge: Program and Abstracts. February 18-22, 2013. Pg. 105.


Rain: A Huge Risk When Not Using Herbicides

Tractor in a Field

Cultivator Stuck in a Wet Field

Farmers who use herbicides to control weeds have great flexibility in the timing of applications. Farmers who use cultivation to remove weeds do not have much flexibility. Cultivation must be done when weeds are small. If a field is too wet for a tractor to enter, cultivation cannot be done and the weeds continue to grow and cause crop yield loss. Recent research shows that the wet field problem is common and that relying on cultivation instead of herbicides results in a yield loss of about 26% one-third of the time.

“Wet weather during the early part of the growing season was the major reason that mechanical weed control was difficult in some years.

This variability fit our observations of the trials that there was a large range in annual grain yields in the organic systems depending on how favorable the weather was for mechanical weed control.

The field crew reported problems controlling weeds in the organic systems in 1993 and 1998 at Elkhorn and 1993, 1996, 2000, and 2001 at Arlington.

Based on the above summary, we estimate that the frequency of weed control problems and subsequent reduced yields in low-input row crops is roughly 34 out of every 100 cases and the corresponding relative yield is approximately 74%.”

Authors: Posner, J. L., et al.
Affiliation: Department of Agronomy, University of Wisconsin.
Title: Organic and conventional production systems in the Wisconsin integrated cropping systems trials: I. productivity 1990-2002.
Source: Agronomy Journal. 2008. 100[2]:253-260.

Herbicide Use in Finland Promoted by the Government in the 1960s

Herbicide Spraying in Finland 1960

Herbicide Spraying in Finland 1960s

Farmers in Finland were slow in adopting herbicide use in the 1950s with only 12% of the acreage treated and fields were overrun with weeds. The Finnish government launched a national weed control program in the 1960s to promote the use of herbicides and herbicide use increased steadily. Today, more than 95% of cereal crop acres in Finland are treated with herbicides annually.

“In Finland, weeds are of relatively great significance because of the open ditch drainage systems in the fields. After the second world war the problem of weeds assumed an even greater importance owing to the mechanization of plant production. In Finland the use of herbicides was not, however, very prevalent in the 1950’s as in most other agricultural countries.

In view of the above facts a national weed campaign was launched in collaboration with agricultural organizations in 1962. The plan of campaign covered a period of three years. The promotion of the chemical control in cereal crops was the foremost object of the first year. Despite adverse climatic conditions the work proved most successful and the field acreage sprayed with herbicides was doubled, covering finally some 300,000 hectares, corresponding to 28% of the total cereal acreage.”

Author: Mukula, J.
Affiliation: Department of Plant Husbandry, Tikkurila, Finland.
Title: National weed campaign of 1962.
Source: Maatal ja Koetoum. 1963. 17:192-200.

Yams are in Decline, Herbicides Can Help


yam (left); sweet potato (right)

The dominant zone for yam production in the world is in West Africa, where about 93% of the world’s production occurs. Yam is a major source of calories for millions of people. Yam produces the highest amount of food calories and protein annually per hectare. Currently, yam farming is very labor-intensive and the crop is in decline.

“Weeds pose an increasingly serious challenge in yam cultivation. Speargrass is a noxious rhizomatous perennial weed found especially in the lowland sub-humid zones of West and Central Africa where it severely constrains crop production. …Chemical control reduces speargrass density leading to higher yields.

As far back as 1982 several authors, as summarized by Diehl… predicted a future decline in yam production based on economic and agronomic considerations. The major issues were shortage of labor, in view of the labor intensive nature of yam cultivation… limited availability of seed yams; declining soil fertility associated with reduced fallow periods; and a reported shift in demand to cheaper commodities in some areas.

More recently a mathematical model, based on FAO data, predicted that yam production could decrease dramatically over the next 15 years. They attributed the predicted decline to a combination of high costs of production, inadequate yields, losses in storage and unfavorable prices to farmers.

The cost of labor in yam cultivation (about 40% of total variable cost) is high and increasing. Yam farmers are ageing and have increasing difficulty in coping with the challenges of cultivation. Increasing urbanization is leading to increased labor shortage and cost. Yam production systems will benefit from:

…increased use of mechanization and other labor-saving practices (e.g. use of herbicides).”

Authors: Asiedu, R., and A. Sartie.
Affiliation: International Institute of Tropical Agriculture, Nigeria.
Title: Crops that feed the world 1. yams.
Source: Food Security. 2010. 2:305-315.

Brazil: The World’s Future Rice Bowl?


For the past several years, Brazil has caught much of the attention of the global rice market. The large increase in rice production in Brazil, its expanding share in the international rice markets and its highly valued quality rice have made it recognized as a major player in the global rice market. Herbicides have played a major role in the increase in rice production in Brazil.

“Weedy red rice is one of the main problems in most of the rice-growing regions of the world because it decreases rice grain yield and milling quality. …The development of imidazolinone herbicide–resistant rice cultivars has allowed selective control of weedy red rice in the rice crop. This technology has been used across approximately 1.1 million ha in Brazil and the same area in the United States, and is under development in several countries in South and Central America, Central Europe, and Asia. The use of imidazolinone herbicides on imidazolinone-resistant rice cultivars has improved the control of red rice and led to the adoption of better crop management practices. In Brazil, this system started to be used in 2003, and since 2007 these processes resulted in an increase of approximately 40% in the mean rice grain yield in southern Brazil. Similar benefits have also been observed in other areas where this technology has been used.”

Authors: Goulart, C. G. R., et al.
Affiliations: Federal University of Rio Grande do Sul, Brazil.
Title: Distribution of weedy red rice (Oryza sativa) resistant to imidazolinone herbicides and its relationship to rice cultivars and wild Oryza species.
Source: Weed Science. 2014. 62:280-293.­ Available:

Warning: The Risks of NOT Using Herbicides


John Nalewaja                                                                             Homer LeBaron

For most people, weeds are usually regarded as innocuous. Controlling weeds with herbicides is practiced on a large-scale every year, largely unnoticed and unappreciated by most people. Scientists who have spent their careers studying weeds (weed scientists) know the potential risks of NOT using herbicides. Two prominent weed scientists have written eloquently about weeds and the importance of herbicides.

“Weeds are the silent, malignant, massive natural force which invades agricultural fields and paddies, spreads to deplete the soil moisture, devours the plant nutrients, and deprives crops of sunlight with severe devastation to crop yields. Weeds endanger the quantity of our food, feed, and fiber and enslave millions of men, women, and children in emerging nations to a laborious life of weeding with primitive methods and tools—machete, sickle, and hoe—just to escape starvation from day to day.”
-Nalewaja, J.D. 1972 [1]

“I maintain that never in history have so few done so much for so many in providing food and improved standard of living as weed scientists.  We have enjoyed a phenomenal success in providing the only consistent, dependable, efficient and economical means of weed control the world has ever known, even leading to surplus production on fewer acres…. We must educate the public and policy makers on the risks of not using herbicides.”
-LeBaron, H.M. 1990 [2]

Authors: [1] Nalewaja, J. D. [2] LeBaron, H. M.
Affiliations: [1] North Dakota State University [2] Syngenta.
Titles: [1] Weeds: coexistence or control. [2] Weed science in the 1990s: will it be forward or in reverse?
Sources: [1] Journal of Environmental Quality. 1972. 1(4):344-349. [2] Weed Technology. 1990. 4:671-689.

An Ancient Practice on an Ancient Crop: Hand Weeding Lentils



The lentil is a bushy annual plant grown for its edible seeds. Lentils have been part of the human diet since Neolithic times, being one of the first crops domesticated in the Near East. Lentils are an essential source of inexpensive protein in many parts of the world. Health magazine has selected lentils as one of the five healthiest foods. The ancient practice of hand weeding lentils is no longer practical.

“Lentil is among few legume species adapted well to dry conditions in traditional rainfed cereal based farming system in Turkey. Due to extensive government support for the production of lentils in order to reduce large areas left annually to fallow, its acreage and production have sharply increased over the last two decades. Currently, lentil is grown on 517,000 ha land in dry areas and its production reached 380,000 t. However, long term national yield increased only marginally in consequence of unfavorable cultural practices, especially weed control.

Lentils because of their small stature do not grow tall and do not build up a protective canopy to prevent establishment of weeds. Therefore, lentils are poor competitors and good weed control is essential for successful production… Yield losses due to weeds in lentil of 40-80% have been reported.

Hand weeding is practiced in traditional production areas, but is impractical in the extensive production areas. Hand weeding is labor-intensive and therefore an expensive operation when done by hired labour and, if delayed, the operation does not prevent adverse effect of the weeds on crop yield. The use of appropriate herbicides can eliminate this early weed competition and prevent yield losses. It is therefore necessary that effective herbicides should be used to reduce unwanted competition.

In conclusion, two years of trials showed that herbicide applications considerably increased lentil yields compared with the unweeded control under Erzurum’s dry conditions.”

Authors: Elkoca, E., et al.
Affiliation: Department of Plant Pathology, Ataturk University, Turkey.
Title: Effects of chemical and agronomical weed control treatments on weed density, yield and yield parameters of lentil.
Source: Asian Journal of Plant Sciences. 2004. 3[2]:187-192.

Australian Wheat Yields Have Doubled Thanks to Herbicides

Australian Wheat Yield 1930-2010 (Trendlines)

Australian Wheat Yield 1930-2010 (Trendlines)

Australian wheat-growing areas are dry. Historically, tillage was used to remove weeds, but tillage further dried out the soil. Herbicides have made it possible for Australian wheat farmers to stop tilling entirely. As a result, soil moisture retention has increased and wheat yields have doubled.

“An analysis of the yield trends of wheat production in Australia showed that yields have increased by an average of 12-13 kg ha-1 year-1 over the past six decades, despite rainfall not changing and irrigated wheat contributing only a very small proportion to total production. A more recent analysis of wheat yield trends in Australia and the various states of Australia has shown that since the early 1980s there has been a more rapid increase in yield of over 30 kg ha-1 year-1. In Western Australia, where wheat is not irrigated and rainfall has probably declined over the last 25 years, the increases… arise solely from increases in rainfall-use efficiency.

However, the major impact of agronomic management on rainfall-use efficiency has not arisen from increasing total water use by the crop in evapotranspiration, but from increasing water use by the crop itself in transpiration at the expense of water loss by weeds or from the soil by soil evaporation, deep drainage, surface runoff, or lateral throughflow.

The use of minimum tillage or conservation tillage, whereby residues from the previous crop are left on the surface, weeds are controlled by herbicides rather than tillage, and the seed is sown with minimum disturbance of the soil surface by the use of narrow tines, has led to reduced losses of water by soil evaporation and increased yields. Further, minimum tillage systems allow earlier planting as delays resulting from using tillage to remove weeds are reduced.”

Author: Turner, N. C.
Affiliation: CSIRO Plant Industry.
Title: Agronomic options for improving rainfall-use efficiency of crops in dryland farming systems.
Source: Journal of Experimental Botany. 2004. 407[55]:2413-2425.

Restoring Nature in Hawaii with Herbicides

Paintball gun herbicide warfare

Paintball gun herbicide application

The Nature Conservancy is the leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. Invasive weeds are a major threat to natural areas and herbicides have made it possible to remove these unwanted species.

“Kaua’i is rugged and beautiful, but it is also threatened by a host of invasive plants and animals. One of those invaders is the Australian tree fern, a fast-reproducing ornamental that was brought to Kaua’i almost half a century ago to prettify resorts on the island’s North Shore. It rapidly grows frond to frond and crowds out native plants.

“I’ve been fighting weeds for 20 years and I’ve never seen anything like the Australian tree fern,” says Trae Menard, The Nature Conservancy’s director of forest conservation in Hawaii. “It’s a pretty bad weed.”

In 2001, The Nature Conservancy launched its program to fight the invaders. 

Much of the research and development has focused on the Australian tree fern—“an ecosystem dominator,” as Menard puts it—that has exploded across the island. Menard and his team have developed a wide-ranging arsenal that includes “the Stinger,” a precision herbicide dispenser slung underneath the helicopter, which Hobbs and other pilots use to spray individual Australian tree ferns. The team has also tested herbicide-packed pellets that can be fired by a crew member in the helicopter with a paintball gun. That kind of precision targeting, along with a formula tailored to the Australian tree fern, has allowed the weed fighters to kill a lot of plants with extremely small quantities of Imazapyr, a relatively short-lived herbicide that has almost no effect on animals.

“We treated over 4,000 tree ferns in a 5,000-acre area over a three-year period,” says Menard, “and we only used 11 gallons of herbicide.”

But the tide may be turning in the fight to save Kaua’i’s native forest. More than 90 percent of the mapped Australian tree ferns in  Wainiha Valley have been treated and killed, and Menard’s team is now preparing to attack ferns in neighboring Lumaha’i valley.”

Author: Jenkins, M.
Affiliation: Reporter.
Title: Pacific Invasion: on the Hawaiian island of Kaua’I, scientists are pioneering new technologies to combat a surge of superweeds that threaten native forests.
Source: Nature Conservancy. September/October 2013. Pgs. 51-59.

Herbicides Improve Productivity of Traditional Maize Farmers in Mexico

Milpan Cultivation

Milpa Cultivation

Milpa cultivation involving cutting an area of forest, burning, and planting crops has existed in the Yucatan Peninsula for more than three millennia. Fallow periods are short and decreasing, leading to a productivity collapse of the system. Technologies that increase yield and maintain plots under cultivation have the potential to decrease the land area needed for family food production, resulting in more mature forests.

Management practices are needed that increase yield in the first year of cultivation, and maintain yield with continued cultivation. Obvious solutions for achieving these outcomes, considering the hypothesized limitations from weed competition and nutrient depletion, are herbicides and fertilizers.

In milpa, weeds and pests were traditionally controlled manually; however, pesticide use has become more common.

For any cultivation year, labor requirements were much greater for hand control than for chemical control.  …If chemical control can be implemented effectively it represents an opportunity for farmers to reduce labor input, and continue to cultivate the same land for a longer period.

At harvest, herbaceous weed cover was much less following chemical control than with hand or no weeding and with chemical control, there was no increase in weed pressure between cultivation years suggesting that chemical weed control could enable cultivation of the same land for an extended period.

…with hand weed control, grain yield declined with continuing cultivation while grain yield did not decline with continuing cultivation when chemical control was implemented.

This suggests that maintaining weed control through chemical application benefits the crop throughout the growth cycle.

The study suggests that both enhanced weed pressure and declining fertility are important factors for yield decline in milpas. Chemical weed control required much less labor than hand weeding, effectively reduced weed cover, and increased grain and biomass yield. Grass weeds were not problematic in the first year of cultivation. However, continued cultivation led to problems such as yield decline unless chemical control was used.

Authors: Parsons, D., et al.
Affiliation: University of Tasmania, Australia.
Title: Managing maize production in shifting cultivation milpa systems in Yucatan, through weed control and manure application.
Source: Agriculture, Ecosystems and Environment. 2009. 133:123-134.