Angular leaf spot caused by Pseudocercospora griseola is the most destructive disease of common bean (Phaseolus vulgaris L) in the Southern Highlands of Tanzania (SHT). The objectives of this study were to assess the farming system and farmers awareness in the ALS disease prone environments of the SHT. A structured questionnaire was designed to collect information from 238 respondents sampled from Mbeya, Njombe, Iringa and Rukwa regions. Data collected included population demography, production constraints, and indicators of poverty. The results showed that ALS widely occurred in the SHT but farmers were not aware of the disease and sources of inocula. Most of the respondents were poor with average yields of less than 500 kg ha -1 . Lack of knowledge on ALS disease and the presence of favorable environmental conditions increased chances of P. griseola proliferation. Therefore, trainings on awareness and intensification of extension services is important. Breeding for durable resistance is an overriding consideration towards increasing bean productivity in the SHT.

Phytates and tannins are present in varying proportions in legume based foods. Investigation on the effect of cooking on tannins and phytates was carried out on thirty eight raw and cooked bean (Phaseolus vulgaris) varieties. Tannins were assayed by vanillin-hydrochloric acid method, while phytates were determined by a method developed by Haugh and Lantzsch. There was a very high significant difference (P≤0.00001) in the tannin concentrations between the raw and cooked bean samples. The mean tannin content for the raw and cooked samples was 1.168±0.81 and 0.563±0.503%CE, respectively. Reduction of tannins after cooking ranged from 20%CE in M'mafutala to 81%CE in GLP 2 with an average reduction of 56.3%CE. Equally, there was a very high significant difference (P≤0.0001) in the phytate concentrations between the raw and cooked bean samples. The mean phytate content for the raw and cooked samples were 0.0219±002 and 0.0122±003 µg/mL, respectively. Cooking reduced the anti-nutritional factors significantly (p≤0.0001). The extent of antinutritional factors reduction varied between bean varieties. Cooking is therefore important for mineral absorption during digestion process in humans as it makes the minerals less bound and hence physiologically available.

Angular leaf spot (ALS) caused by Pseudocercospora griseola is among the devastating diseases of common bean (Phaseolus vulgaris L.) in the Southern Highlands of Tanzania (SHT). This study was conducted to assess the agronomic performance and economics of yield loss associated with the disease on five bean cultivars that are widely grown by farmers. The cultivars were evaluated in a split plot design with a randomized complete block arrangement during 2012/2013 and 2013/2014. The main plots were two rates of fungicide and a control whereas the subplots consisted of cultivars. Data were collected on disease severity, yield, and yield components. Analysis of variance was done and marginal rate of returns determined using partial budget. Results indicated significant decrease in yields, number of pods, seeds, and seed weight at P < 0.05 for untreated plots. Decreases in yield were associated with ALS disease severity that in turn was influenced by cultivar and rate of fungicide used. Higher grain yield losses of as much as 61% and the lowest marginal rate of returns were recorded for unsprayed plots during heavy rains. Fungicide usage at the recommended rates should be considered during heavy rains and breeding for resistance should be taken as an economical and sustainable strategy for managing the disease.

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