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.

Herbicide Use in Corn Benefits Cotton and Peanut Farming

Herbicide Use in Corn: Treated (L) Untreated (R)

Herbicide Use in Corn: Treated (L) Untreated (R)

In southern states, corn is often planted in a three-year rotation with peanuts and cotton. One of the values of having corn in the rotation is that effective herbicides that are used in the corn crop control populations of weed species that would be difficult to control in the peanut and cotton crops. Thus, the control effectiveness of the corn herbicides benefit the succeeding peanut and cotton crops.

“Corn in a Deep South crop rotation remains one of the best weed management tools or decisions a grower can make – when he can make it. A corn crop squeezed into a field at least every three years in a corn-cotton-peanut cycle is most effective.

“There is an inherent value to a good crop rotation that is likely priceless, especially in the long-term weed management of a farm,” says Eric Prostko, weed specialist with the University of Georgia Cooperative Extension.

For corn particularly, its arsenal of herbicides is a welcomed addition to fields, he says, noting that most common field corn herbicide programs farmers use all give similar weed control results.

“But for one big reason, corn is the only major crop we grow where we don’t have to use a PPO (protoporphyrinogen oxidase) herbicide. Atrazine is carrying the load for us with corn” he says.

That herbicide’s economic, broad-spectrum weed control is certainly a plus, but the biggest benefit it brings to fields in the Deep South is its control of pigweed – a problem that isn’t going away.

For south Georgia farmer Philip Grimes, the atrazine-glyphosate one-two punch that his corn rotation provides is essential to his management of herbicide-resistant pigweed that showed up on his farm a couple of years ago.”

Author: Haire, B.
Affiliation: Reporter
Title: Corn in rotation a strong weed management tool
Source: Delta Farm Press. 2014-01-17.

Fungicides Prevent Destruction of Pistachio Orchards in California

Alternaria leaf blight

Alternaria leaf blight

Alternaria late blight infects both leaves and fruit, causing early defoliation, severe brown-black stains on the shells and mold contamination of the shells and kernels. Other damage from Alternaria includes poor flavor and possible mycotoxin contamination. Without fungicide applications, alternaria would reduce California pistachio production by 30-50%.

“Alternaria late blight (ALB), caused by Alternaria alternata, A. tenuissima, and A. arborescens, is now considered the most destructive disease of pistachio in California. The disease affects foliage and fruit and is an annual production concern for pistachio growers. On foliage, it can be recognized by the development of large necrotic lesions, and multiple, expanding lesions eventually consume the whole leaf. The lesions are black in the center due to the production of many spores and are surrounded by a chlorotic halo. Under optimal conditions for the disease, the fungus can defoliate a tree in late summer and autumn. On fruit, it is characterized by small necrotic lesions surrounded by a red halo. These are located on the hull of immature nuts. When the nuts develop, one or two lesions can penetrate and decay the hull, resulting in shell staining of the nut underneath. The staining of the shell and colonization of the kernel result in a reduction of the nut quality. Although cultural practices such as irrigation management and pruning to increase air movement and decrease air humidity in the orchard can help reduce ALB, the use of multiple fungicide applications is essential to achieve adequate disease control.”

Authors: Avenot, H. F., et al.
Affiliation: Department of Plant Pathology, UC-Davis.
Title: Sensitivities of Baseline Isolates and Boscalid-Resistant Mutants of Alternaria alternata from Pistachio to Fluopyram, Penthiopyrad, and Fluxapyroxad.
Source: Plant Disease. 2014. 98[2]:197-198.

Herbicide Use by African Rice Farmers is Spreading Rapidly Due to Benefits

Hand Weeding Rice in Africa

Hand Weeding Rice in Africa

In Ghana, recent farmer surveys show that herbicide use by rice farmers is high. The adoption of herbicides is not due to programs being promoted by international organizations. Rather, the high adoption is simply due to farmers learning about the benefits of herbicides from other farmers.

“There was strikingly high use of herbicide in rice plots, with 84 percent of rice area treated with herbicide across all rice ecologies. Fifty-eight percent of rice area was treated with herbicide before planting, and 69 percent of the area was treated with herbicide after planting.

The yield of plots with herbicide is significantly higher than that of plots without herbicide for all rice ecologies…. For irrigated plots with fertilizer and certified seed, there was a 3.1 ton/hectare difference between plots with and without herbicide.

A simple comparison of weeding costs suggests that farmers using herbicide spend 666 cedi/hectare total in purchasing herbicide (8 liters at 8 cedi/liter) and an additional 86 person-days for manual weeding, while farmers not using herbicide spend 1,477 cedi/hectare for manual weeding for 211 person-days on average. It is apparent from this calculation that it is cheaper to purchase herbicide than to hire or use family labor for weeding.

The diffusion of herbicide seems to be wide, and farmers are learning about it from other farmers. About half of farmers reported that they knew about herbicide and its benefits from advice by or observing other farmers’ plots. …This suggests that if a technology is beneficial, it can spread quickly among farmers.”

Authors: Ragasa, C., et al.
Affiliation: International Food Policy Research Institute.
Title: Patterns of Adoption of Improved Rice Technologies in Ghana.
Source: IFPRI. July, 2013. Working Paper #35. Available at: http://www.ifpri.org/publication/patterns-adoption-improved-rice-technologies-ghana

Organic Coffee Farmers in Central America May Not Survive

Coffee Fields

Coffee Fields

Organic coffee farms in Central America have typically been located at high altitudes where there has been less worry about fungal   disease. However, in recent years, fungal outbreaks have increasingly-occurred at these higher elevations and organic growers may not survive the huge yield losses due to their non-use of fungicides.

“Finca Santa Isabel, often held up as a shining example of success with organic agriculture in coffee, may not make it. The culprit? A fungus known as roya that often goes unnoticed until bright-orange pustules start appearing on the underside of leaves. This parasite interrupts the tree’s ability to nourish itself by redirecting nutrients to those colorful lesions. Eventually, the infected leaves shrivel up and fall off.

The Keller family owns Finca Santa Isabel, located in Santa Rosa, about an hour south-east of Guatemala City. It became the second estate to be Rainforest Alliance-certified in 1997, and the Kellers were named Sustainable Standard-Setter by the nonprofit in 2003. In a 2009 profile, the family was lauded for its successes with sustainable practices: caring for the land, being a profitable business, and having enough left over to help build needed infrastructure for their community. They grow Arabica at an elevation of 3,500 to 4,500 feet above sea level in a zone most growers thought roya could not thrive.

But the rusk outbreak is happening almost everywhere. By most accounts, large and low-lying estates accustomed to spraying to protect their trees will survive. …Growers in areas prone to the rust use fungicide prophylactically twice a year. Spraying, which typically occurs in July and September in Central America, is timed to happen just before and just after periods of heavier precipitation.

Farmers caught unprepared, like Keller, have to decide whether and how to fight this blight.

The fungus is causing huge shortfalls in coffee cherries at higher elevations and in shaded areas of Central America, in places where growers used to feel relatively immune. Keller was one of them and he relayed a stunning loss: “Last year, we had about a 70% drop in production and so did many other farms that work conventionally around us. The main reason is that nobody thought that it was going to be so bad.”

Guatemalan workers on coastal farms in lower altitudes that face the Pacific sprayed ahead of time. Farmers in these regions have also planted rust-resistant varieties as part of recovering from earlier outbreaks. Those growing coffee in hillier areas at higher altitudes did not. Nor do they use fungicides routinely.

“…The pathogen itself could be adapting to temperature variation or it could be a combination of the weather events with growers not using fungicides making disease more severe.”

Authors: J. Neill
Affiliation: STiR
Title: Central American Coffee Rust Crisis: No Easy Answers.
Source: STiR Tea and Coffee Industry International. Available at:  http://worldcoffeeresearch.org/files/2013/12/2013Jul-STiR-CoffeeRustCrisis.pdf

Insecticides Defend Florida Avocado Trees from Invasive Species


The redbay ambrosia beetle is an invasive species that vectors a fungus, Raffaelea lauricola, that causes laurel wilt, a lethal disease of several plant species within the Lauraceae, including avocado… The spread of the fungus has affected large areas of native Lauraceae trees in the southeastern United States and is now threatening the avocado industry in south Florida.

“In February 2012, the first avocado tree in a commercial grove located in the northeastern quadrant of the avocado growing area was diagnosed with R. lauricola. As of July 2013, 90 trees have been diagnosed R. lauricola positive, and >1,900 symptomatic trees have been removed as part of a suppression and sanitation strategy. …Because of the lack of alternative pest management strategies (e.g. biological control, repellants, etc.), private landowners and avocado producers rely on applications of chemical insecticides to complement sanitation practices and protect trees in groves affected by this beetle-disease complex.

The current strategy is based in early detection and removal of diseased trees to eliminate beetle breeding sites and fungal inoculum sources. The diseased trees are uprooted, the stump and roots burned, the trunk and limbs are chipped, and the chips and adjacent trees are sprayed with insecticides.”

Authors: Carrillo, D., et al.
Affiliation: Tropical Research and Education Center, University of Florida.
Title: Potential of Contact Insecticides to Control Xyleborus glabratus (Coleoptera: Curculionidae), a Vector of Laurel Wilt Disease in Avocados
Source: Journal of Economic Entomology. 2013. December.

New Fungicides Improve Management of Vomitoxin

Fusarium Head Blight

Fusarium Head Blight

Fusarium Head Blight (FHB), also known as scab, is a destructive disease of wheat and other small grains. In the spring, ascospores and/or conidia are released from crop residues and are spread by wind or splashing water. They land on wheat heads and during wet, warm weather they germinate and infect glumes, flower parts, or other parts of the head.

In addition to lowering grain yield and quality, F. graminearum produces mycotoxins, primarily the trichothecenes deoxynivalenol (DON), nivalenol (NIV) and T-2 toxin. …These mycotoxins are harmful to humans and livestock. In North America, DON, also known as vomitoxin, is the most common and economically important mycotoxin found In Fusarium-infected wheat. …Grain with high concentrations of DON often is discounted or rejected at the elevator, which exacerbates the losses incurred by the farmer.

“In the U.S., a less than desirable number of current commercial wheat cultivars have moderate resistance to FHB and this resistance can be overwhelmed in years with high disease intensity. Fungicides are often applied to control FHB when favorable conditions for disease development are forecast.

Over the last two decades, there has been considerable improvement in the effectiveness of fungicides in controlling FHB and DON. This improvement is attributable in part to improved fungicide chemistries and greater knowledge gained through research on fungicide application rates, timing, and technology.

The best approach to managing FHB is to integrate available management strategies. Research has shown that integrating cultivar resistance with fungicide application can be effective management strategy for FHB.

Availability of moderately resistant cultivars and new fungicide chemistries coupled with improved fungicide application technology has led to greater farmer adoption of an integrated strategy in the management of FHB and DON.”

Authors: Wegulo, S. N., et al.
Affiliation: Department of Plant Pathology, University of Nebraska-Lincoln.
Title: Integration of fungicide application and cultivar resistance to manage fusarium head blight in wheat.
Source: InTech. Fungicides – Showcases of Integrated Plant Disease Management from Around the World. Available at: http://www.intechopen.com/books/fungicides-showcases-of-integrated-plant-disease-management-from-around-the-world

Herbicides are Widely-Used by Maize Farmers in Ghana with Great Benefits

Weedy Maize Field in Africa

Weedy Maize Field in Africa

Ghana leads the way in terms of herbicide use by maize farmers in Africa. Farmers applying herbicides are enjoying higher maize yields, less need for backbreaking handweeding, and lower costs of weeding.

“Herbicide is widely used among maize farmers in Ghana. Seventy-three percent of maize area was applied with herbicide either before or after planting.

Figures in Ghana are far higher than earlier estimates for Africa south of the Sahara: 3 percent adoption among maize smallholders in Africa south of the Sahara.

Plots treated with herbicide have a significantly higher average yield than those without herbicide, with the greatest difference in the Northern Savannah zone. In plots with fertilizer and certified seed, those with herbicide have 1.4 tons/hectare more yield than those without herbicide in the Northern Savannah zone.

Given serious labor constraints and the relatively cheaper herbicide formulations available, herbicide use has been popular across all regions. Comparison of weeding costs suggests that whereas farmers using herbicide spend 359 cedi/hectare total in purchasing herbicide (9 liters at 8 cedi/liter) and an additional 41 person-days for manual weeding, farmers not using herbicide spend 511 cedi/hectare for manual weeding for 73 person-days on average. It is apparent from this calculation that it is cheaper to purchase herbicide than to hire labor or use family labor for weeding.”

Authors: Ragasa, C., et al.
Affiliation: International Food Policy Research Institute.
Title: Patterns of Adoption of Improved Maize Technologies in Ghana.
Source: IFPRI. July, 2013. Working Paper 36. Available at: http://www.ifpri.org/publication/patterns-adoption-improved-maize-technologies-ghana

Fungicides Prevent Significant Yield Losses in Argentinian Wheat Fields

Wheat Rust is a Common Problem in Argentina

Wheat Rust is a Common Problem in Argentina

Argentina is one of the countries with the largest wheat-growing area in the world with more than 5 million hectares spread all over the country.

The grain production region has experienced severe tillage changes in the past twenty years, mostly due to the increased interest in maintaining soils covered with plant residues.

No tillage can reduce costs by decreasing fuel consumption required to produce a crop. However, in the wheat/soybean system under no tillage, as in wheat following wheat, the inoculum of fungi may survive until the next wheat season. Therefore, the use of fungicides is essential to decrease the severity of diseases.

Fungicides are usually applied on foliage to control diseases but they are also used for seed treatments to prevent seed decay. Leaf rust, septoria leaf blotch, and tan spot are the most important diseases in terms of potential yield reduction in Argentina.

“Planting resistant cultivars is one of the least expensive and most effective management strategies to prevent diseases. However, cultivars with an adequate genetic resistance level to necrotroph foliar diseases are scarce, and usually resistance to leaf rust is complete, conditioned by one or a few genes and has a low level of durability in Argentina. Therefore, chemical protection together with cultural practices is a common method of control. In addition, fungicides are also important because Argentinian wheat region combine high yield potential cultivars with high infection pressure, both deriving from adequate temperature and moisture levels, large application of N fertilizers and rotations dominated by cereals, which promote progression of some foliar diseases.

The results of experiments carried out in Argentina indicate that sowing wheat following wheat in no tillage is possible without significant yield losses if effective disease management practices including moderately resistant cultivars, N fertilization and fungicides are applied.”

Authors: Simon, M. R., et al.
Affiliation: National University of La Plata, Argentina.
Title: Recent Advances on Integrated Foliar Disease Management with Special Emphasis in Argentina Wheat Production.
Source: InTech. Fungicides – Showcases of Integrated Plant Disease Management from Around the World. Available at: http://www.intechopen.com/books/fungicides-showcases-of-integrated-plant-disease-management-from-around-the-world

No Small Wonder Why Farmers Use Herbicides

Soybean Growth With and Without Herbicide Treatments

Soybean Growth With and Without Herbicide Treatments

Farmers all over the world use herbicides to prevent weeds from taking over their fields. A large number of non-chemical methods of weed control have been tested and are available. However, farmers prefer herbicides. A prominent weed scientist cites the reasons why…..

“In comparison with herbicides, non-chemical methods of weed control are often: less effective, more unpredictable, more expensive, have labour/timeliness constraints, may not reduce the requirement for herbicides, may provide little or no visual evidence of success, may have adverse environmental implications and are often more complex to manage.”

Author: Moss, S. R.
Affiliation: Plant and Invertebrate Ecology Department, Rothamsted Research, Hertfordshire, UK.
Title: Weed research: is it delivering what it should?
Source: Weed Research. 2008. 48:389-393.