RESUMO
Weeds are among the limiting factors that influence low production of economically important crops including cashew (Anacardium occidental L.). Shrub weeds attribute to inter-competition for resources, hinder harvesting and ultimately reduce cashew yields in Tanzania. The current study determined the distribution, characteristics and chemical control option of Dichapetalum Engl in Lindi and Mtwara regions, Southeastern Tanzania. The distribution study involved a survey for weed presence along the areas of Lindi and Mtwara regions. The characterization included distilling, and assessing the growth and development properties of shrub weed. Chemical herbicides; glyphosate 480g. ai/l, 2, 4 D - Dichlorirophenoxyacetic 720g. ai/l, triclopyr 160g a.i./l and 1:1 mixture of glyphosate 480g a.i./l plus triclopyr 160g a.i./L at 15, 20 and 25 mls of formulated product/L of water per 4 m2 were tested on tender, mature and blooming growth stages of D. Stuhlmannii and three spraying frequencies. Findings revealed that the D.stuhlmannii, is a widely distributed shrub weed in Lindi and Mtwara regions. The weed was characterized with three main growth stages of seedling, mature and blooming with a long tap root and evergreen throughout the wet and dry seasons. The tested herbicides revealed the potential suppression of D. Stuhlmannii growth. Glyphosate and a mixture of glyphosate + triclopyr at 15 ml/L outperformed triclopyr and 2, 4 D across all the growth stages. Double spraying of glyphosate and its mixture bettered frequencies of triclopyr and 2, 4 D. The delayed regrowth of suppressed shrub weed took 90-120 days after application of herbicides. The current study recommends for single or double applications of glyphosate herbicides at 15 ml/L or 10,700 ml/ha on tender or mature D. Stuhlmannii in cashew farms. Further studies on the economic feasibility and effect on the microbiota of applied fungicides are required.
RESUMO
This study was conducted out to evaluate the soil fertility in under the cashew tree canopy and nutritional contents of cashew trees on the Makonde Plateau in southeast Tanzania. Seven villages were included, all of which were geographically close to one another yet had the same agro-ecology. The cashew plant samples were taken above the same longitudinal segment as the soil samples, which were taken in under canopies of cashew trees. Nitrogen, Phosphorus, Potassium, Magnesium, Calcium, and micro nutrients (Iron, Zinc, Sodium, and Copper) were all examined in the samples. However, soils were analysed for Organic Carbon, Organic Matter, and pH with soil samples taken at two different depths of 0-30 cm and 30-50 cm, these tests were conducted during the wet and dry seasons. The results confirmed that Calcium, Magnesium, Sodium, and Iron varied significantly with soil depth, as well as with soil depth, seasons, and their interactions, for Organic Carbon and Organic Matter. During the wet season, Nitrogen, Phosphorus, and Zinc concentrations in cashew trees were all statistically higher. Nitrogen and Phosphorus were significantly strong and positively (r = 0.95) correlated in cashew plants with respect to all other nutrients, suggesting synergistic effects. These results imply that macro nutrients including Nitrogen, Phosphorus, Potassium, Magnesium, and Calcium, and micronutrients such as Iron, Zinc, Sodium and Copper limit cashew production in the research area. It is necessary to determine site-specific recommendations and dosages for these nutrients.
