Tanier (Xanthosoma spp.) constitutes an impor tant dietary component with high market demand in Puerto Rico. However, tanier production in Puerto Rico has decreased dramatically in recent decades, largely because of a condition known as dry root rot (mal seco). One of the soil conditions known to enhance dry root rot is poor drainage, particularly when it occurs in sequence with drought periods. We examined tanier growth and yields in a very poorly drained upland Ultisol under three soil management treatments: 1) planting on the flat; 2) planting on ridges; and 3) planting on ridges with perforated tile drain tube placed at the base of the ridges. All treatments included drip irrigation management to prevent drought stress at any crop growth stage. Water table observation pipes were installed to monitor water table fluctuations. Yields of marketable cormels for treatments 1, 2 and 3 were 5.38,19.94 and 17.61 t/ha, respectively. Yields for the two ridged treatments (with and without tile drainage) were not statistically different at the p = 0.05 level, but both treatments produced yields statistically greater than that of the non-ridged control treatment. Mean water tab le depth remained within 50 cm of the soil surface during most of the growing season, and on some sampling dates was within 30 cm of the soil surface inspection of soil friability by hand at harvest time showed that even 10 months after initial tillage, the soil retained a loose structure with low mechanical impedance. Results indicate that on poorly drained clay soils with good structure, high yields of tanier can be obtained by planting on ridges under drip irrigation, with no additional benefits obtained by installing aeration tubing. The need to monitor water tables on poorly drained upland soils is also indicated.
Suppression of violet root rot, caused by Helicobasidium mompa, with a fertilizer paste applied to soil surface around the base of apple trunks.