Fitopatologia Brasileira (2007) 32, 146-149

Maria E. Salustiano, Edson A. Pozza, Antônio C. Ferraz Filho and Paulo E. Souza (2007)
Expansão da pústula da ferrugem em três cultivares do cafeeiro
[Rust pustule expansion in three coffee cultivars]
Fitopatologia Brasileira 32 (2), 146-149
Abstract: Lesion expansion is considered an important epidemiological component in various pathosystems. To evaluate rust pustule expansion (Hemileia vastatrix) in three coffee cultivars and the respective lesion expansion rates (LER) under controlled conditions, the following assay was carried out. The experiment was installed in plant growth chambers at a temperature of 20 ± 2 ºC and relative humidity of 70 %. Twenty three-month-old plants of each cultivar were inoculated with 0.5 mg/mL of a uredospore suspension. Seven pustules from each cultivar were randomly marked on the 42^nd day after inoculation in the abaxial leaf surface. They were photographed daily with a digital camera for 15 days, for later area estimation using the UTHSCA Image Tool program. Every digital image was standardized at 4.0 x 4.0 cm. The production of uredinospores/cm² in the lesion was evaluated by placing the uredinospores in microtubes containing 1mL of water with 0.05% Tween 80 at the end of the experiment. Concentration was determined using a hemacytometer. The curves of pustule expansion progression in the three cultivars were adjusted to the exponential model. The rates of lesion expansion were 0.14, 0.16 and 0.16 mm²/day and the number of urediniospores produced was 918.6, 929.3 and 934.8/cm² for the cultivars Acaiá, Catuaí and Rubi, respectively. There were no differences between the three susceptible cultivars, in relation to the rates of lesion expansion and the final production of urediniospores. These results may contribute to better knowledge of possible mechanisms that act to increase rust severity, without the occurrence of new infections.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Portuguese)
Full text of article

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Hemileia vastatrix	Coffee (Coffea)