Influence of Timing of Herbicide Application on Winter Canola Performance
Canola (Brassica napus L.) is an important source of vegetable oil for humans and canola cake is a nutritious feed for animals. However, weeds are one of the major constraints in canola production in the southeastern regions of the United States causing loss upto 50 percent in yield. Control of weeds in spring canola has been reported but research on weed control in winter canola has not been well documented. Therefore, research experiments were conducted from 2005 to 2007 to evaluate the effects of herbicide application timings on canola performance. Results showed that pre-emergence timing of trifluralin @ 1 kg ai ha resulted 496 kg ha , 411 kg ha , 502 kg ha higher canola yield as compared to control in 2005, 1 1 1 1 2006 and 2007, respectively. Pre-emergence application timing of trifluralin gave 79% less weed biomass than control plots. Increasing weed density and weed biomass significantly reduced the canola yield whereas increasing plant height increased the canola yield significantly. This study revealed that herbicide application timing significantly reduced weed biomass and increased canola yield.
Non-Chemical Weed Control in Winter Canola (Brassica napus L.)
Cultural practices, management techniques and product quality are important factors which can influence the field heath and food security. Application of low input agriculture strategies, like as organic farming will result to high quality and safe products. In order to reduce herbicide use and enhancing quantity and quality of canola seed (cultivar Hyola308) a field experiment was conducted at Varamin, Iran, on 2007- 2008 growing season. Seven experimental treatments consisted of Chemical weed control using Trifluralin (2.5 l.ha -1 ) + sethoxydim (1.0 l.ha -1 ), integrated reduced dose of the same herbicides to between rows cultivation, twice cultivation, integrated pre-irrigation (25 days before sowing) to cultivation at stem elongation stage, black plastic mulch, weed-free and uncontrolled weed were arranged in randomized complete blocks with four replications. Results indicated that canola grain yield, yield components, oil percent were significantly decreased due to weed interference. The highest crop height, leaf area index, grain and oil yield obtained from black plastic mulch treatment. This non-chemical treatment has also significantly reduced weed density and dry matter. However there was no significant difference between plastic mulch and integrated control treatments (pre-irrigation + cultivation). Since mulching practices in trade canola fields is so difficult and relatively expensive, simple integrated (agronomic and mechanical) weed control treatment including irrigation the field 25 days before planting with the aim of removing emerged winter weeds via seedbed preparation practices + cultivation at stem elongation stage could be recommended.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.