Control of Morningglories (Ipomoea spp.) in Sugarcane (Saccharum spp.)
Abstract Morningglories are summer annual or perennial dicots, and are troublesome weeds in sugarcane cultivated in northern India. If not controlled, they may compete with sugarcane, interfere in the harvest operation, and reduce yields. Managing morningglories in sugarcane continues to be a serious challenge for sugarcane growers. Field experiments were conducted during the 3-yr period from 2007 to 2009 to evaluate herbicides applied PRE and POST for control of morningglories in sugarcane. The herbicides applied PRE included diuron, metribuzin, and atrazine at 1.6, 1.4, and 1.0 kg ai ha−1, respectively, applied alone or followed by 2,4-D amine salt (0.58 or 1.16 kg ae ha−1) or 2,4-D sodium salt (0.8 or 1.6 kg ae ha−1) applied POST. Herbicides applied PRE controlled morningglories ≤ 87% at 15 d after treatment (DAT); however, control reduced to ≤ 56% at 90 DAT. Control improved when herbicides applied PRE were followed by POST application of 2,4-D amine or sodium salt. For example, diuron applied PRE followed by 2,4-D amine salt applied POST at any rate provided 100% control of morningglories at 15 and 30 DAT. At 90 d after POST application, control ranged from 68 to 82% with the PRE followed by POST herbicides, compared to 0% control when metribuzin or atrazine were applied PRE alone. The density and biomass of morningglories was also reduced to zero in treatments that included 2,4-D amine salt. The number of millable canes, cane height, and single cane weight was superior in PRE followed by POST herbicide treatments compared to herbicides applied PRE alone. Maximum cane yield was recorded for the treatments that included 2,4-D amine or sodium salt compared to only PRE treatments, and it was usually comparable with the nontreated weed-free control. It is concluded that a combination of PRE and POST herbicides were effective for control of morningglories; however, more research is required to evaluate other herbicides and their tank mix partners for control of morningglories in sugarcane. Nomenclature: Japanese morningglory, Ipomoea nil (L.) Roth.; obscure morningglory, Ipomoea obscura L. Ker Gawl.; sugarcane, Saccharum spp.
High-Temperature Effects on Germination and Survival of Weed Seeds in Soil
Seeds of eight weed species were heated for up to 7 days at 40, 50, 60, and 70 C in dry (2% moisture) and moist (19% moisture) Bosket very fine sandy loam to determine temperature-time treatments lethal to weed seeds. Seeds in dry soil were very tolerant to 60 C or less for up to 7 days but most seeds were killed at 70 C after 7 days. In moist soil, a few (1 to 12%) seeds of common purslane, redroot pigweed, johnsongrass, and spurred anoda survived for up to 3 days at 70 C. Some (4 to 30%) seeds of velvetleaf, pitted morningglory, and the above species survived up to 7 days at 60 C. No seeds of prickly sida and common cocklebur survived more than one-half day at 60 C. Three days at 50 C were lethal to all cocklebur seeds. Many of the sublethal treatments promoted germination of prickly sida, velvetleaf, spurred anoda, and pitted morningglory, presumably because high temperature broke dormancy of some hard seeds. The enhanced effect of heat treatments upon seeds in moist soil compared to seeds in dry soil was due to the higher moisture content of seeds, or in fruit tissues of dispersal units in moist soil. Because some seeds survived several days in moist soil at 60 and 70 C, it is unlikely that soil solarization or other natural methods of raising soil temperature will eliminate weed seeds from the field. However, high soil temperatures may reduce weed seed populations by killing heat-susceptible seeds and by breaking dormancy of hard seeds followed by thermal kill of seedlings.
Drivers of Live Cattle Price in the Livestock Trading System of Central Cameroon
Livestock production and trade are critical for the food security and welfare of rural households in sub-Saharan Africa. In Cameroon, animal trade consists mainly of live cattle commercialized through livestock markets. Identifying the factors contributing to cattle price formation is critical for designing effective policies for sustainable production and for increasing food availability. In this study, we evaluated the influence of a range of individual- and market-level factors on the price of cattle that were sold in all transactions (n = 118,017) recorded over a 12-month period from 31 livestock markets in the main cattle production area of the country. An information-theoretic approach using a generalized additive mixed-effect model was implemented to select the best explanatory model as well as evaluate the robustness of the identified drivers and the predictive ability of the model. The age and gender of the cattle traded were consistently found to be important drivers of the price (p < 0.01). Also, strong, but complex, relationships were found between cattle prices and both local human and bovine population densities. Finally, the model highlighted a positive association between the number of incoming trading connections of a livestock market and the price of the traded live cattle (p < 0.01). Although our analysis did not account for factors informing on specific phenotypic traits nor breed characteristics of cattle traded, nearly 50% of the observed variation in live cattle prices was explained by the final model. Ultimately, our model gives a large scale overview of drivers of cattle price formation in Cameroon and to our knowledge is the first study of this scale in Central Africa. Our findings represent an important milestone in designing efficient and sustainable animal health management programme in Cameroon and ensure livelihood sustainability for rural households.