Coffee is the popular beverage name for a species of plants of Coffea genus cultivated for their beans that are used for preparing stimulating drinks. They are small evergreen shrubs with multiple stems and smooth leaves; bear green fruits that become crimson when ripe and normally contain two coffee seeds or beans. The trees can live for 20-30 years. Coffee primarily comes in two varieties, Arabian coffee (C.arabica) and Robusta coffee (C.cenephora) and originates from Africa. They grow in a wide range of soil but generally prefer deep, well draining loam with pH between 5 & 6.
Among the coffee producing countries India is the 6th largest producer and exporter of coffee in the world after Brazil, Vietnam, Columbia, Indonesia and Ethiopia with the state of Karnataka accounting for 71% production followed by Kerala at 21% and Tamil Nadu at 5% with an annual production of 8,200 tons. Both Arabica coffee and Robusta are produced in the proportion of 32:68. Indian coffee is unique because it is grown under the canopy of shady trees (a popular Agroforestry practice) making it one of the most eco-friendly crops in India that helps preserve the bio-diversity in the eco-sensitive Eastern and Western Ghats.
Coffee production in India steadily rose from 1951 to 2002 after which there was a huge slump for almost a decade owing to drop in global market and prices of coffee, occurrence of drought and outbreak of pests and diseases. Peak production was achieved in 2011-2012 because of responsive measures to mitigate the problems listed above. While the problem with prices and global market was left for economists, the remaining two domains required in-house mitigation.
Measures proposed included:
Development of drought tolerant and pest / disease resisting species
Development of irrigation and water retention technologies
Development of pest and disease management methods.
The Central Coffee Research Institute has been actively trying to develop new breeds of resistant crops but it has a long way to go and long term programs for high yield crops and disease resistant strains is a matter of uncertain future right now. Emphasis is laid on the present practices to sustain the production while creating minimal impact on soil health, plant and environment and the need for integrated management of pests and diseases and Eco-friendly biocide disinfectants.
The common pest and diseases occurring at coffee cultivations are listed herein:
1) Bacterial Blight: Caused by Bacterium Pseudomonas syringae, the disease can spread over long distances through infected seedlings or via water splash in the field. Symptoms include spots on leaves leading to necrosis on lamina and shoot tips that spread down the branches leading to dead leaves on branches. Only mitigation is use of protective pesticide spray.
2) Cercospora Leaf spot: Caused by Fungus Cercospora coffeicola, it spreads by wind, water splash and human movement through wet fields. Symptoms include brown spots on foliage and red leaf margins, premature shedding of leaves and infected discolored disfigured berries. Use of pesticides in case of occurrence of disease.
3) Coffee Berry disease: Caused by Fungus Colletotrichum kahawae, very serious disease that spreads within the plantation by air / water / physical contact media and can destroy 80% of the harvest. Symptoms include lesions on green berries, premature fall offs and mummified berries. Protective sprays of pesticides and removal of infected berries are the only remedies.
4) Coffee leaf rust: Caused by Fungus Hemileia vastatrix, it spreads by air and water. Symptoms include lesions on ventral sides of leaves, infection starts from near the bottom of plant and infected leaves drop off premature leaving twigs and defoliated branches. Spraying fungicides and total removal of infected plants seem to be the only remedies.
5) Rootknot Nematodes: Nematodes are wormlike organisms that attack the root system of plants, feeding on the sap. They can form knots in the roots that inhibit the plant from properly feeding. Meloidogyne exigua, M. incognita, M. coffeicola, Pratylenchus brachyurus, and P. coffeae are the most common species of rootknot coffee nematodes. Symptoms of a nematode infestation are galls, splits, scales and decreased mass in the root system, and chlorosis and defoliation in the upper plant. They are among the most harmful coffee diseases and pests. Application of pesticides seems to be the only preventive option.
Pesticides and Fungicides:
Copper and its compounds have had a wide-ranging employment in agriculture. It has been used as an active ingredient in various pesticidal and fungicidal formulations to protect crops from major fungal leaf and fruit diseases. Around 6% of world copper production is used in agriculture which directly affects the environment and represents the most important source of copper dissipation directly into soil and environment. It was not before 1880s that accidentally copper's fungicidal properties were discovered by French Scientist, Millardet and from 1885 the Cu-based Bordeaux mixture officially became the first fungicide to be used on a large scale world-wide. Copper based fungicides are inorganic compounds that have a multi-site activity with low risk of pathogen developing resistance at any stage; hence popularly used as agricultural pesticides to control fungi, bacteria, and in some cases invertebrates and algae. Following absorption into the pathogen, the metal ions link to various chemical groups present in many proteins and disrupt protein functions. Thus the mode of operation is non-specific denaturation of cellular protein. Copper hydroxide fungicide and Copper sulfate fungicide are the most common salts of copper used as plant fungicides.
It is applied in two possible ways:
a) Contact Fungicide: These are applied but not absorbed by the plant. They act on surface and prevent infection and germination of the infective propagules of the pathogen. They are sprayed in advance and produce a toxic barrier against pathogen infestation. The biggest limitation is the need to be applied at regular intervals to prevent new growth flushes.
b) Systemic Fungicide: These are absorbed through the foliage and roots and transported around the plant in vascular tissues. Thus lower doses and less frequent application is required. They are applied after the infection has occurred to treat symptoms and eradicate the disease mostly during seed treatments or by root dips, in-furrow treatment or soil drenching. They are site specific and hinder particular metabolism functions. They are expensive; sometimes induce defoliation of the plant and often the pathogens become resistant through simple cellular mutations.
Even though it's an efficient biocide, copper is still a heavy metal & long years of accumulation in soil and water does have its environmental consequences. Heavy metals tend to accumulate and persist in agricultural soils for a long time. A study conducted by Savithri et al. (2003) in India confirmed significant copper accumulation in surface and subsurface soils due to extensive use of Bordeaux. Horticulture operations with long history of copper fungicide were the main culprits. It is well presumed, heavy metals present in soil may have negative impacts on human health and environment.
i) Copper accumulation in soil above threshold values may be responsible for phytotoxicity to higher plant species and associated soil properties. The phenomenon is mainly observed in acidic soils with pH <6; just the type of soil coffee plants prefer. This can disturb the overall productivity of Agroforestry farms present in India
ii) Copper biocides have negative effect on soil pH, available phosphorous and organic matter. When in soil, it binds to organic matter, clay minerals and hydrated metal oxides thus making them unavailable to plants. It has been been to suppress nitrogen fixation by Rhizobium.
iii) Earthworms are known as farmer's friend. Their feeding and burrowing activities help regulate organic matter in soil and maintain soil porosity. Copper residues negatively affect soil microbial activity and earthworm population and processes like bioturbidation. Thus depleting soil health.
iv) They affect the working and life cycles of naturally occurring bio-pesticides and bio-controls, reduce efficiency of mycorrhizal inoculations.
v) Regardless of accuracy of application, copper fungicide spray has the possibility of drift risks & metal contamination in adjacent field damaging non-target sensitive crops and plants, especially in Agroforestry practices.
vi) Runoffs from farms containing dissolved copper and copper sulfate toxicity is fatal to aquatic fauna.
vii) Long term exposure to copper can cause irritation to nose, mouth and eyes, headaches and vomiting; accidental ingestion of contaminated foods may cause copper poisoning and liver and kidney damage in humans.
Silver Hydrogen Peroxide: An eco friendly agricultural biocide
Silver Hydrogen Peroxide, as the name suggests is a synergized composition of hydrogen peroxide stabilized with silver ions in the form of silver nitrate or infused Silver Nano particles. Hydrogen Peroxide is a strong oxidizer formed by combination of water with ozone. The bonds between the molecule and oxygen atom are unstable and easily break releasing free oxygen that oxidizes organic matter. Thus H2O2 disinfects by oxidizing cell membranes and inner cell structures of pathogens. It is a great biocide; being a strong oxidizing agent.
H2O2 is stabilized using silver so as to increase its efficacy. Silver acts both as a stabilizer and an activator. In addition to this, silver is shown to have certain disinfectant properties of its own. Addition of silver greatly reduces the quick decomposition of H2O2. In presence of silver, the peroxide decomposes only in presence of biological contaminants. The decomposed H2O2 oxidizes the cell wall, cell membrane and cytoplasm of the pathogens, the DNA is destroyed thus killing the organism. Silver is known to react with certain proteins in the DNA and act as a biostat, inhibiting further growth of the pathogens.
Hydrogen Peroxide and Silver are neither toxic nor produce DPBs upon decomposition. It dissociates producing water and oxygen and the residual silver has been proven to have no ill effects on man and environment. Breaking into water and oxygen, it is world's safest biocide and eco disinfectant. At recommended concentrations of application, it is harmless to the plant and soil biota except pathogens.
The most impressive feature of Silver Hydrogen Peroxide is its varied modes of application:
A properly diluted solution of the biocide can be spouted or fumigated on wet soil 12 hours prior to plantation of fresh saplings. This kills most disease causing organisms.
A diluted biocide solution can be directly fed to plant roots by drip lines at stipulated growth periods to prevent re-growth of infectious pathogens.
Soil can be directly drenched with a diluted solution in the early growing season to eradicate most of the pathogens that infect at early stages of growth.
Foliar spraying in the early morning at periodic intervals can keep leaves free from rust and commonly occurring fungal infections
Pruning tools can be sterilized in a diluted solution before operations to minimize infection by contact.
Fresh seeds can be soaked in a diluted solution prior to planting to prevent pathogen infestation during germination stage.
Mature beans can be washed in a dilute biocide solution to remove organic and inorganic residues increasing shelf life and processing operations.
Silver Hydrogen Peroxide is by far the best all purpose multi-utility biocide because:
It is effective against all kinds of bacteria, viruses, yeast, mold, nematodes and spore formers
It is Environmentally friendly – practically 100% degradable breaking down to water and oxygen
Does not create odor or alter the taste of beans
Highly effective over long periods even at very high water temperatures and low pH
Has no toxic effect in its diluted state
No carcinogenic or mutagenic effect
Long shelf life: maximum loss of concentration 3% per year
Does not harm other plant parts
Equipment and operation costs are low, can be easily applied without fear of environmental residue