Economic Importance of Weeds

Pigweed

Figure 1. Pigweed

Introduction

There are over 250, 000 plant species in the world. About 30, 000 0f them occur as weeds in various agro-ecosystems and about 18, 000 of these cause serious damage to crops throughout the world.

Weeds today are considered to be the most important pest group which interferes with utilization of land and water resources. The losses caused by them to horticulture are greater than any other pest category.

Definition

Some of the several definitions given to the term “weed” are listed below.

A weed is a plant:

  • Growing where it is not desired
  • Out of place
  • Growing where something else should grow or nothing should grow
  • Whose potential for harm is greater than for good
  • Extremely noxious, useless or poisonous
  • Whose economic value has not been discovered

Careful examination and analysis of these definitions indicate that the term “Weed” is very much relative to a situation, time, and to an individual concerned.

In general, due to the following reasons, weeds are undesirable plants at any place and time and have to be managed:

  • Weeds Cause Yield Reduction Of Crops Through Competition And Allopathic Effect

1. Competition for Nutrients

Analysis of mineral composition of common weeds and crop plants indicates that the former accumulate high concentration of plant nutrients in their tissues and in many cases, they are more than those found in common crop plants.

2. Competition for Solar Energy

About 99% of the dry matter of plants are composed of organic matter which depend upon solar energy for production. Production potentials of crop plants shaded with weeds are greatly reduced and they may even appear chlorotic and weak.

3. Competition for Water

For producing equal amount of dry matter, weeds in general transpire more water than most crop plants. This may be of importance in dry land agriculture where moisture is very often a limiting factor.

4. Competition for Space

Competition for space may be both in the atmosphere as well as in the rhizosphere preventing the crop plants respectively from photosynthesis and moisture and nutrient uptake.

5. Allopathic Effects

Allelopathy involves any direct or indirect harmful effect on another plant through the release of chemical compounds on the other. These chemical compounds may inhibit seed germination or reduce growth of other plants.

  • Weeds Harbour Other Pests

Weeds growing in the crop fields, harbour insects disease organisms and other pests. Outside the fields, weeds often act as alternate or parallel hosts to crop pests which migrate to the main fields. Control of these pests should also be undertaken, which enhances the cost of plant protection.

  • Weeds Reduce the Quality of Farm Produce

Weeds reduce the quality through admixture of weed seeds which produce odd odours, increase moisture contents and cause the produce in warehouses to heat and rot. Fruits and vegetables are discoloured and malformed under the impact of weeds.

  • Weeds Increase the Cost of Labour and Equipment

Because of weeds, more time and labour are spent on land preparation and cultivation, cleaning, irrigation and drainage channels and harvesting and cleaning produce. Likewise, maintenance and repair costs tools and equipment also would increase.

  • Weeds Contaminate Water Bodies and Increase Water Management Problems

Weeds impede navigation, reduce flow rate of irrigation water by 50% or more, and clog irrigation and drainage channels, increase evapo-transpiration by 130 – 250%.

Kafue Weed

Figure 2. Kafue Weed

Therefore, for the formulation of a sound weed management programme, thorough knowledge of the weed problem in an area or a farm, their prevalence, density, frequency, association with crops and their changing patterns under field conditions is required. Hence, a floristic survey of the region or one’s own farm should be able to help identify the weeds.

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Sustainable Integrated Pest Management for Tomato

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Tomato damaged by Black Mold

INTRODUCTION

Integrated Pest Management (IPM) is the coordinated use of pest and environmental information with available pest control methods to prevent unacceptable levels of pest damage by the most economical means and with the least possible hazard to people, property, and the environment. IPM is a sustainable approach to pest management that uses knowledge of pest, crop and environmental conditions to select the best combination of the following IPM tactics:

  • Cultural control – modifying farming practices to decrease pest problems
  • Biological control – use of beneficial organisms to regulate pests
  • Chemical control – use of chemical pesticides appropriately
  • Physical control – killing pests directly or by disrupting their environments

TOMATO PESTS AND THEIR CONTROL

Insects - Nematodes Affecting Tomatoes

Insects/ Nematodes Affecting Tomatoes

Cutworms are green or brown caterpillars that curl into a C shape when disturbed. They eat young plants at the soil line at night, and can leave a healthy seedling cut off entirely and lying on the ground.

Controls: Eliminate weeds around garden beds at least two weeks before planting. Hand-picking cutworms at night may help, or you can protect seedlings with cardboard collars or one or more toothpicks (inserted close and parallel to the stem).

Aphids affect tomatoes, especially vigorously growing ones.

Controls: A handful of aphids won’t hurt a healthy tomato plant, but if new leaves are curling or the shoots are coated in aphids, crushing aphids by hand or blasting them off with a strong jet of water will control them.

Hornworms are voracious eaters of tomato plants and fruit. They are large (1” to 4”) green caterpillars with a prominent horn on the tail end; they will eat leaves, small stems, and fruit, sometimes stripping young plants entirely. The mature caterpillars drop to the ground and pupate in the soil over the winter.

Fruitworms, also known as corn earworms, are about an inch long, pale green or brown, sometimes striped. They burrow under the stem end of tomato fruit to create messy warrens full of brown frass.

Controls: Hand-picking caterpillars in the early evening, when they are most active, is quite effective.

Rototill or thickly sheet-mulch beds to destroy pupae between seasons. Bacillus thuringiensis or spinosad sprays, both organic, can help with control. General predators, such as praying mantises or wasps, also reduce populations.

Stinkbugs are an annoyance to tomato growers, as their feeding can cause corky white patches under the skin of ripe tomatoes. These patches don’t peel easily when cooking or canning the fruit.

Controls: Hand-pick stinkbugs or snip them with garden shears; a bucket of soapy water held under them can help, as they often drop when disturbed. Eliminate weeds around garden beds at least two weeks before planting. Insecticides are not recommended.

Snails and Slugs can be a problem, especially if plants are on or near the ground. They rarely bother foliage on mature tomatoes, but they can eat large chunks of ripening fruit if they have easy access.

Controls: Keep tomato plants and especially fruit off the ground by using cages or staking.

TOMATO DISEASES AND THEIR CONTROL

Fungal and Bacterial Pathogens of Tomatoes

Fungal and Bacterial Pathogens of Tomato

Early Blight is a common leaf spot caused by the fungus Alternaria solani. Dark brown spots with broad yellow haloes appear on the leaves, and concentric rings can be found in the spots under bright light.

Stems and fruit can also be infected. It often progresses from the bottom of the plant upward. Cool humid weather or overhead irrigation encourage Early Blight, which is spread by splashing water and germinates on moist leaves.

Controls: Avoid getting water on the leaves whenever possible, change the locations where you plant your tomatoes, mulch well around each plant, and clear away all dead or infected plant material at the end of each season. Picking off infected leaves may slow the progression of the disease until the weather is more favourable.

Speck and Spot are bacterial diseases with similar symptoms, causing small black specks or patches on leaves, stems, and fruit. They can be distinguished from Early Blight by the water-soaked appearance of the spots, and the fact that the spots don’t cross the larger veins. Like Early Blight, these bacterial diseases are spread by water, and they can overwinter in soil and on debris from the previous season.

Controls: Prevent and control these diseases as you would Early Blight, above. Bacterial spots stop spreading in dry, warm weather. Chemical controls are usually not needed.

Late Blight is caused by Phytophthora infestans, a fungal disease most famous for the Irish potato famine. It is just as serious in tomatoes, causing dark green to purple-brown water-soaked spots that grow quickly on leaves and stems. The underside of infected leaves will sometimes have whitish powdery spores. Fruit turns brown but stays firm. The fungus thrives during periods of high humidity and mild temperatures (60-78° F). Once it gets going, it can kill a plant very rapidly and spread to other tomatoes, peppers, or potatoes.

Controls: Avoid sprinkler irrigation, very dense planting, or other things which keep humidity high.

Remove volunteer potatoes or tomatoes, and clean up debris at the end of the season. Mulching may help prevent initial infection.

Fusarium Wilt is caused by a soil-borne fungus (Fusarium oxysporum) which infects the roots and stems of tomatoes. Leaves yellow and wilt without spots, sometimes only on one side of the plant, and brownish streaks creep up the inside of the main stem and into the branches. Symptoms are worst in warm weather, especially as the first fruits are getting large. It is usually fatal to infected plants.

Controls: Fusarium can survive a long time in the soil, and it is spread by shoes, garden tools, and anything else which moves soil around. The typical solution in an infected garden is to grow resistant varieties (look for an F or FF on the variety label); no systematic resistance trials have been done for heirloom varieties. Cleaning up all tomato debris, including old roots, and solarizing the soil may help.

Verticillium Wilt (Verticillium dahliae) is similar to Fusarium Wilt, and it can be difficult to tell them apart, though Verticillium prefers cool temperatures rather than warmth.

Controls: Management is the same as for Fusarium Wilt; resistant varieties carry a V on the label.

Powdery Mildew can appear in late summer or fall as the nights cool, but it rarely causes much damage.

Irregular yellow blotches with a faint coating of white powder form on the leaves, and eventually cause brown dead patches.

Controls: No control is necessary on mature plants, but in the case of young or severely affected plants, sulphur dust provides good control.

SUMMARY

Pesticides and application costs are nearly 25% of tomato grower’s expenses. Despite all the planning and preparation that goes into planting a garden, insects and diseases can still frustrate even the best gardeners.

REFERENCES

Integrated Pest Management (IPM)- Rodents

Pests and Diseases for Home Gardeners

Precautions & Application Tips on Specific Pesticides

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Plant Breeding, Genetic Engineering and Quality of Cultivars

INTRODUCTION

AMONG the variety of agricultural and technical factors that determine the quality of field crops, fruit and vegetables, the choice of a specific cultivar by the grower, i.e., the choice and combination of genes controlling economically important traits, may be considered the most initial step for defining quality and productivity. It is the factor that determines farmers’ potential output long before any other agricultural measures are taken and even before the seed is sown in the field or greenhouse. As a consequence, the breeding of a cultivar that is adapted to specific demands of the farmer and the consumer may be considered as a preharvest factor per se, even if certain quality characters of this cultivar apply to postharvest stages.

The classical approach for breeding cultivars is to select suitable phenotypes or mutants, which are then crossed, selfed, cloned or combined with populations depending on their reproductive biology (Table 2.1). A major drawback of this approach is that for most agronomically important traits, the phenotypic variance is the base for selection, which, however, is not only composed of the genotypic variance but also comprises an environmental component as well as interactions between genotypes and environment. This tends to obscure selection progress and is one of the reasons why breeding for quantitatively or polygenically inherited traits is so tedious and time-consuming.

Table 2.1. Approaches in Plant Breeding

Classical Breeding

• Selection of phenotypes

• Intercrossing, selfing, vegetative cloning of favourable phenotypes

• Inbred line or population or clonal varieties

Marker-Assisted Selection

• Mapping of quantitative trait loci (QTL) (e.g., solids content and pH of

tomato pulp, chips quality of potato, β-glucan content of barley)

• Selection of genotypes instead of phenotypes

Genetic Engineering

• Gene suppression by antisense or cosuppression

• Expression of foreign genes (constitutive or tissue-specific)

• Overexpression of native genes

 

In addition, a combination of positively acting polygenes of one specific genetic background is difficult if not impossible because of recombinational dispersion of genes in each sexual generation. Biotechnology and molecular biology have provided exciting new tools to the plant breeder, which may help to circumvent some of the obstacles in the breeding of complex traits.

BIOTECHNOLOGY AND PLANT BREEDING

Plant breeding has been impacted during the last two decades by a number of technological developments that may enrich plant breeders’ repertoire to achieve breeding progress more quickly or conveniently or even allow them to design plant traits that were impossible to create by classical breeding methods. Besides classical breeding methods, biotechnological breakthroughs like in vitro fusion and regeneration of plant cells, and marker-assisted selection (MAS) of monogenic traits as well as the tracing of quantitative trait loci (QTL) by use of molecular genomic markers have gained increased importance for plant breeding (Table 2.1). In tomato, e.g., QTL for quality traits such as soluble solids content, fruit mass, fruit pH, and fruit shape have been mapped (Grandillo et al., 1996). In potato, traits such as chip colour, tuberization and tuber dormancy may be traced by molecular markers. For these characters, between 5 and 13 QTL have been identified. In some cases relatively high individual effects of a single QTL were found. Also, the total phenotypic variation of a given trait that could be accounted for by combined assessment of these QTLs was in the range of 50% or higher, which demonstrates the potential of molecular markers as a selection tool for tracing quantitatively inherited traits.

Limitations of MAS relate to the fact that applicability of these markers often depends heavily on the specific experimental population in which they were identified, as well as on the extent of marker polymorphism, linkage disequilibria and linkage phases among the individuals under selection. In addition, specific marker technology and know-how is required for routine marker-assisted selection programs, rendering the cost efficiency of MAS uncertain for crops that are not of major economic importance.

As a more recent achievement, transformation methods enabling the transfer of any isolated gene into virtually any important cultivated plant species have opened the toolbox of genetic engineering as a novel opportunity to the plant breeder. Plant transformation technology allows breeders to circumvent some restrictions of classical breeding methods.

In particular, gene technology offers the breeder the following promises:

  1. The manipulation of native and the introduction of foreign specific genes not only allow for modification of simply inherited traits like herbicide tolerance and virus and insect resistance, they also open new horizons for directed adjustment of even traits that display very complex inheritance in native systems. Thus, in some instances approaches of factorial instead of quantitative genetics may be sufficient for the breeder to cope with the improvement of specific quality or even yield-determining characters.
  2. Genetic engineering provides “added value” by transferring specific genes to cultivars that have been subject to intensive breeding efforts and, thus, are highbred already with respect to yield, uniformity, disease resistance, and so on. This aspect cannot be underestimated since any modern cultivar is defined by a complex of characteristics that have been assembled during years or decades of breeding work. In classical breeding new or better characteristics have to be introduced by crosses, giving rise to sexual recombination and, as a consequence, to dispersion of the valuable trait complexes in the progeny. In addition, undesired genes from the donor cross parent are also introduced, which have to be eliminated by successive backcrosses to the cultivar parent. It is for this reason that plant breeders tend to prevent the introduction of “exotic,” i.e., agronomically unadapted donor genotypes into their highbred elite gene pools. The addition or modification of single genes to elite lines by genetic engineering would help to alleviate these difficulties.
  3. Genetic engineering speeds up the breeding process and provides better cultivars to farmers and consumers with less effort of labour and time. There is expectation that the concerted use of biotechnological methods may substantially shorten the breeding cycle for a given crop, which presently is in the range of 10–15 years or, for some woody fruit species, extends to 25 years. This time span appears quite large if one considers the need for the breeder to adapt his breeding goals to the rapidly changing requirements by growers, industry, traders and consumers.

CONCLUSION

It should be stressed, however, that biotechnological methods such as genetic engineering are not, and most probably will not become, self-sufficient in breeding better cultivars. Rather, they may provide additional tools to the breeder who will still have to apply classical breeding methods, which continue to constitute the backbone of plant breeding.

The genetic engineering approach relies on (1) a detailed knowledge of the biochemical pathways that generate the quality trait, (2) the isolation of genes that have an impact on these pathways, and (3) the transfer and expression of one or several of these genes into crops in order to specifically modify the trait of interest. A number of strategies are available to genetically engineer a trait.

First, if the plant to be modified expresses a gene leading to undesirable characteristics, this gene may be shut down by introducing the same gene once more into the plant but in the opposite direction so that transcription of the native gene is neutralized by its antisense counterpart.

Gene silencing can also be achieved by introducing a truncated version of the native gene in either direction, a phenomenon that is called cosuppression. Second, if expression and not suppression of genes is desired, then novel genes that are not originally owned by the plant may be introduced from any source organism and may be expressed either constitutively or specifically in a tissue or developmental stage. Finally, the plant’s own genes may be expressed more abundantly by inserting additional copies of them or by combining these genes with different promotors which drive gene expression more efficiently than the gene’s native promotor.

REFERENCES

Shewfelt, R. L. 1985. Postharvest treatment for extending the shelf life of fruits and vegetables. Food Technol., 40(5): 70–72,74,76–78, 80 and 89.

Shewfelt, R. L. 1999. Fruit and vegetable quality, in Fruit and Vegetable Quality:

An Integrated Approach, R. L. Shewfelt and B. Brückner, eds., Technomic

Publishing Co., Inc., Lancaster, PA.

Shewfelt, R. L., Erickson, M. E., Hung, Y-C. and Malundo, T. M. M. 1997. Applying quality concepts in frozen food development. Food Technol., 51(2):

56–59.

Simmonds, N. W. 1979. Principles of Crop Improvement, Longman, London.

Sloof, M., Tijskens, L. M. M. and Wilkinson, E. C. 1996. Concepts for modelling the quality of perishable products. Trends Food Science Tecnol., 7: 165–171.

Steenkamp, J. B. E. M. 1989. Product Quality: an Investigation into the Concept and How It Is Perceived by Consumers. Ph.D. thesis, Agricultural University

Wageningen, The Netherlands.

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Economic Impact of Aflatoxin Contamination in Groundnuts Production

Introduction

Aflatoxin is known in chemistry science as a mycotoxin that, thus a micro dangerous chemical substance produced as a secondary metabolites by Aspergillus Flavus and Aspergillus parasiticus fungi. These fungi are widely studied due to their effect on humans and animals, as well as the economic implications thereof (Galvez et al, 2003; Chinnan & Resurreccion, 2013; Kaaya, 2014).

Aflatoxin, like foot-and-mouth disease, hinders the export of African products and agricultural produce to lucrative European, US and rich Asian markets. Often the communities have little knowledge of the existence of such problems and their socio-economic impact. In general, the communities do not have solutions to the problems caused by these diseases, as they do not fully understand them.

Economic Impact of Aflatoxin Contamination in Groundnuts Production

Aflatoxin has been identified as the major problem in groundnuts trade for African countries who are losing about $760 million annually due to contamination of groundnuts (FAO, 1997; Kaaya, 2014).

Smallholder producers suffer the biggest losses both socially and economically, as they lose much of their produce to rotting and contamination caused by moulds and fungi. They are also prone to diseases caused by consuming higher level of aflatoxin.  About 40 percent of burden of diseases in Africa South of Sahara are related to consumption of high levels of Aflatoxin (Kaaya, 2014; Williams et al, 2004).

It is expensive to remove aflatoxin in contaminated groundnuts, raising processing costs. This promotes cost transfer behaviour amongst value chain actors. On the other hand, about 40 percent of disease burden in Africa is related to Aflatoxin contamination, affecting farm labour especially for smallholder farmers, reducing their time and cash investment in their farming businesses, and a threat to their health. Aflatoxin is linked to liver cancer, kwashiorkor, retarded growth in kids and animals, malaria and HIV. Due to pronounced health risks, many countries and trading blocs have imposed strict control measures on international groundnuts trading to safeguard their citizens and improve food safety. However, aflatoxin contamination can be reduced to acceptable levels through raising awareness amongst smallholder producers, investing in quality management as well as crafting and implementing favourable policies that encourage investment in aflatoxin mitigation.

Aflatoxin as a chemical substance is difficult to destroy without destroying the contaminated food. Once groundnuts are contaminated, it will be difficult to eliminate aflatoxin from them. Food processing usually requires low to medium temperatures of between 0 to 180° to cook or roast. Aflatoxin can only be eliminated at temperatures of over 480° (Kaaya, 2014).

Processing aflatoxin contaminated nuts into consumer ready products does not eliminate aflatoxin in groundnuts. If the groundnuts have high levels of contamination, then the end product will also contain higher levels of toxic substances. This in turn exposes the consumers of such products to higher levels of intoxication by aflatoxin and increases the risks of contracting aflatoxin related diseases.

The major economic effect of aflatoxin contamination in groundnuts to smallholder groundnuts farmers in developing countries, including Mozambique is poor marketability of their produce in international markets and poor prices in domestic markets that lead to lower net income to producers and other chain actors.

Taking the case of Zambia, groundnuts is considered one of the most important legumes cultivated on larger farm land area and as a replacement cash crop in place of tobacco that is now facing more stringent regulation in the international markets. Groundnuts are considered a very important source of protein for lower income families in both urban and rural areas, as well as smallholder producers (Times media group, September, 2014). However, higher levels of aflatoxin contamination hinder the exportation of surplus or tradable groundnuts to lucrative markets. Like in Mozambique, less than 5 percent of groundnuts produced are controlled for aflatoxin in the domestic markets, exposing domestic consumers to higher negative health risks (Times media group, 2014). Lack of control by the ineffective Bureau of standards in Zambia and Mozambique means that aflatoxin contaminated ready-to-eat products, floods the domestic markets in both countries. These products can be locally produced or imported.

Aflatoxin contamination lowers the net revenue of all market participants, in an effort to reduce contamination and improve quality of the groundnuts available for processing. This is caused by purchase price dynamics and sorting cost, as in most cases off grades are discarded. Poor post harvesting practices by smallholder producers increases the risk of purchasing sorted but aflatoxin contaminated nuts that will require further processing. The risk factor forces most traders to buy unsorted nuts at lower prices and do the sorting and grading. Higher costs often lead the traders to engage in cost shifting behaviour (Economic Research International, 2012).

Price shifting behaviour often affects two ends; the producer-end through lower prices for their produce and the consumer end through higher product prices due to higher production costs. However, in organic produce marketing linked to ‘fair trade’ markets (often), smallholder groundnuts farmers get higher prices and a premium for supplying quality graded produce that are traceable  back to the producer to certify for quality compliance. Consumers consider organically produce food to be safe and are often willing to pay a higher price for the right quality.

Recommendations

To improve competitiveness in African groundnuts value chains, a number of sticking issues affecting both domestic and international trades must be resolved. The most critical issues border on raising awareness of aflatoxin contamination on groundnuts and the socio-economic impact to smallholder producers.

Smallholder farmers’ awareness and understanding of aflatoxin issues and how they affect their livelihood is critical to aflatoxin mitigation. At present, only 5 percent of groundnuts smallholder producers are knowledgeable on the effect of aflatoxin to their health and rural economies. Health issues can be a driver of behaviour change amongst smallholder farmers, especially aflatoxin links to liver cancer and HIV, two well-known killers in rural Mozambique (SATH, 2014).

A three pronged approach to reduce the impact of aflatoxin contamination can help reduce the socio-economic impact on the whole chain actors. The approach may focus on raising awareness amongst smallholder groundnuts farmers and equipping them with post-harvest knowledge to reduce contamination and infection throughout drying, sorting, selecting, de-shelling and storage. Post-harvesting handling techniques must also be perfected by transporters, traders and processors of consumer ready goods.

Several measures can be applied to reduce contamination, including good agricultural practices, control of moisture and temperature in storage. Total Quality Management toolkit, also known as the ‘Blue Box’ has been successful used by Intertek on World Food Program consignments to keep aflatoxin contamination to desired levels (SATH, 2013; Intertek, 2012).

Quality control by traders and processors is critical in improving aflatoxin compliance in groundnuts. If all trades enforce quality guidance in their business processes including buying policies and practices. It is paramount to incentivize quality compliance when purchasing groundnuts from smallholder producers. This will complement the knowledge empowerment programs aimed at raising awareness of the existence of aflatoxin and its socio-economic impact to smallholder producers and all other actors in the groundnuts value chains.

Governments and regional regulatory institutions must critically look at policy measures that can be used to incentivize or encourage investment in aflatoxin mitigation, improvement of trading in aflatoxin compliant groundnuts, both internationally and intra-regionally. This might include harmonization of aflatoxin maximum acceptable levels applied in the region, as well as procedures for sampling and testing. Administrative documentation can also be simplified to improve free flow of groundnuts in the region.

Policies by individual countries might be used to incentivize private sector companies’ engagement in aflatoxin mitigation by investing in the whole groundnuts subsector to become aflatoxin compliant. This will speed up sector-wide compliance and improve competitiveness in both domestic and international markets. Holistic aflatoxin mitigation, though it will not completely eliminate contamination, will reduce the level of contamination of acceptable regulated levels that reduces health risks and increase Africa groundnuts acceptability in international markets. This will boost Mozambican and Zambian economies through increase forex inflows from exports.

Conclusion

Aflatoxin contamination is the major challenge on groundnuts trading by African countries that produce about 95 percent of the world groundnuts crop. In Southern Africa, in particular Mozambique and Zambia, there is poor awareness of aflatoxin contamination and its socio-economic effects to smallholder farmers. Contaminations that emanate from farm gate affect the whole supply chain. However, more contamination occurs on post-harvest handling and management of groundnuts at all levels of the supply chain. The more the produce exchanges hands and change storage conditions, the more the produce is exposed to contamination risks.

Contaminated nuts fetches less in local markets and are not accepted in the international markets due to strict control levels by the individual countries and trade blocs like the EU and South Africa. Reducing contamination and correct management of the crop at both farm levels will increase the value of the crop, acceptability and quality of final products produced from safer groundnuts. Farmers can do more by improving their farming practises and post-harvesting handling of their produce.

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Integrated Pest Management (IPM) – Rodents

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A Rat In Search of Food

Introduction

Integrated Pest Management is an approach to pest management designed to manage pests and diseases with as little damage as possible to people, the environment and beneficial organisms.

Farmers aim at producing high yields and profits from their crops but their efforts are reduced by pests and disease infestations and damage.

Managing any vertebrate pest requires a preventative approach and with mice and rats, it begins prior to harvest. Even if rodent activity appears lower, preventative management still needs to be considered to prevent future damage.

The Types of Damage Caused by Rodents

  • Loss of volume or weight due to their feeding
  • Loss in quality caused by droppings, urine, and hairs
  • Damage to containers such as bags, that results in spillage
  • Health hazards to people who handle the stored products, certain species of mice and rats are carriers of diseases such as plague, weil’s disease (Leptospiral jaundice) rat-bite fever, and salmonella.

While they are different species of rodents with slightly different habitats, the management approach for all is the same. All mice and rats in storage facilities can cause a significant amount of damage.  Nearby corn or soybean fields can provide a fall food source for mice and rats that will then move into the storage facility or the barn.

Controlling vertebrate pests requires multiple approaches, which in general include exclusion, habitat modification, repellents, trapping and rodenticides. In an open and large scale commercial setting, exclusion, trapping or repellents are not effective. This leaves habitat manipulation and rodenticides, and both are needed for a successful mice and rats abatement program.

Habitat modification such as a close mowing of grass in row middles and ditches late in the fall provides a two-fold management purpose – reduce favorable habitat for mice activity and expose rodents more readily to predators that help with population management. Cleaning up fencerows to reduce habitat is also needed.

Rodenticides are another approach in management programs, as they provide the quickest and most practical means of bringing large populations of mice and rats under control. Bait should be applied when dry and fair weather is predicted for at least three days. If there is a great deal of alternate food (fallen mangoes in a block or nearby field corn), baiting might need to be done more than once to be most effective. If mice and rat populations are very high, a second rodenticide application might be needed. As with any pest management program, but especially when using rodenticides, the risks to non-target organisms needs to be taken into account and prevented.

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Lufenuron – A Miracle Pesticide

 

Lufenuron

Lufenuron

Lufenuron, a new pesticide on the market is a benzoylurea pesticide that inhibits the production of Chitin in insects. Without Chitin, a larval flea will never develop a hard outer shell (exoskeleton). With its inner organs exposed to air, the insect dies from dehydration soon after hatching or molting (shedding of its old, small shell).

Lufenuron is also used to fight fungal infections, since fungus cell walls are about one third Chitin.
Lufenuron is also sold as an agricultural pesticide against Lepidopteranseriophid mites, and western flower thrips. It is an effective anti fungal in plants.

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