Effectiveness of climate, cultivar, and fungicide in controlling rust in Asparagus

Three Asparagus (Asparagus officinalis L.) cultivars were evaluated for susceptibility to Asparagus rust (Puccinia asparagi D.C.) at the Kawanda Agricultural Research Institute and Kalengyere Highland Crop Research Centre in Uganda. The experimental design was a split-plot with cultivars as main plots and fungicide treatments as subplots. Two month old seedlings of UC157Fi', 'Jersey Giant' and 'Jersey Hybrid' cultivars were transplanted in the field with inter and intra row spacings of 1.5 m and 40 cm, respectively. Subplots were treated with no spray or weekly spray with 1.4 kg a.i./ha mancozeb (active ingredient 80 wt/wt zinc and manganese ethylene bis-dithiocarbamate). Percentage of plant area infected with rust was taken at both locations. Data on leaf area index (LAI), spear number, spear diameter and yield was obtained at Kawanda. Results revealed that the incidence of rust was higher at Kawanda than Kalengyere. Symptoms appeared at Kawanda in July 1996, while it was first observed at Kalengyere in February 1997. At Kawanda, cultivar UC157F!' was significantly more susceptible to rust infection compared to 'Jersey Giant' and 'Jersey Hybrid', while the reverse was true at Kalengyere. Mancozeb was effective for controlling rust in Asparagus. Plants sprayed with mancozeb had significantly greater leaf area index (LAI) and spear yield than non-treated controls.