Indirect biological control of the coffee leaf rust, Hemileia vastatrix, by the entomogenous fungus Lecanicillium lecanii in a complex coffee agroecosystem. Coffee rust, also called coffee leaf rust, devastating foliar disease of coffee plants caused by the fungus Hemileia vastatrix. Long known in coffee-growing areas. These now offer the most economically effective control of the disease. H. vastatrix also occurs on robusta coffee (C. canephora) but is much less severe.
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As the control de hemileia vastatrix subsequently spread to arabica coffee areas in southern India and other warm, moist coffee-growing areas in South-East Asia, it continued to cause havoc in the coffee industry for full accounts see Large, and Carefoot and Sprott, However, coffee grown at the higher altitudes of these countries for example, western Ghats in India largely escaped the ravages of the disease Muthiah, and the situation eased as control measures based on shade management and use of fungicides were instigated.
Coffee rust is now endemic in all major coffee producing countries and requires control wherever arabica coffee is grown under warm humid conditions.
Effect on Yield The major effect of coffee rust is to cause premature shedding of leaves; this reduces the photosynthetic capacity of the plant and restricts the control de hemileia vastatrix of new stems on which the next season's crop is borne.
Disease severity in one year therefore directly affects the cropping potential in the following year and the disease has an insidious debilitating effect on the plant over successive seasons. The disease can render coffee cultivation uneconomic wherever it reaches epidemic proportions.
Severe disease can also effect the crop of the current season, as defoliation causes carbohydrate starvation of heavily bearing trees. This leads to premature ripening of berries that produce poor-quality, 'light' coffee beans. Because developing berries are a strong physiological sink for nutrients, a condition known as overbearing dieback may occur when shoots and roots die back as nutrients are preferentially translocated to berries.
High relative humidities will not substitute control de hemileia vastatrix free moisture.
- Hemileia vastatrix
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Control de hemileia vastatrix free moisture is absent, exposure to high relative humidity is not sufficient to induce spore germination Nutman, Loss of moisture after germination has been initiated inhibits the whole infection process.
Recovery does not occur even when adequate moisture is reintroduced Kushalappa and Eskes, b. Spore germination is better on young leaves than intermediate and old leaves.
As a consequence, disease spread and development is usually limited to the rainy season, and rust incidence is control de hemileia vastatrix low during dry periods.
The incubation period or time between infection and lesion development is approximately weeks long so that the disease is often evident in the drier seasons.
Temperature is the most important factor other than moisture to control de hemileia vastatrix germination and subsequent infection by the spores. This is also the most important factor influencing disease development. This relationship between temperature, moisture, and incubation period has been developed empirically and with the aid of computer modelling used to predict rust severity and to schedule appropriate fungicide applications Kushalappa and Eskes, a.
On wet leaves, temperature is control de hemileia vastatrix most important environmental factor influencing germination and infection.
Coffee leaf rust (Hemileia vastatrix)
The minimum, optimum, control de hemileia vastatrix maximum temperatures on agar was reported to be On leaves, minimum and maximum temperatures were slightly lower, After infection is successful, the stomatal cavity is colonized and sporulation will occur.
The colonization process is not dependent on leaf wetness, but is influenced greatly by temperature and by the level of host resistance.
The main effect of temperature is to control de hemileia vastatrix the length of time for the colonization process incubation period. Elaborate regression equations have been developed to describe the importance of temperature on this aspect of the disease.
Sporulation or the production of uredspores is most greatly influenced by temperature, moisture, and host resistance. A single lesion produces spore crops over a month period releasingspores.
Hyperparasitic fungi such as Verticillium haemiliae and V. Their use as biological control agents, however, remains underutilized or is impractical. Factors Influencing Disease Development: The important factors are planting density, control de hemileia vastatrix susceptibility, and predisposition of host due to high prior year yields.
Coffee rust | Description, Symptoms, & Control |
The major cultivars are grown are Coffea arabica. Resistance is both complete and partial. Specific resistance genes have been derived from C.