- Vegetables: tomatoes
- Crop Production: cover crops
- Pest Management: weed ecology
Cover crop research has been extensive over the past few decades and this has provided us with considerable understanding of the characteristics and impacts of cover crops and strategies to manage them. But, research has been skewed in favor of winter cover crops over inter-seeded cover crops. Literature on herbicide suppression of living mulches in vegetables is very scarce. This knowledge can be utilized for herbicide reduction by integrating weed-suppressing abilities of vigorous cover crops into the herbicide regime. In this experiment, two leguminous (sub) tropical cover crops species, sesbania (Sesbania sesban (L.) Merr.) and sunnhemp (Crotalaria juncea L.), will be evaluated in wide-row, transplanted, fresh market tomato (Solanum lycopersicum L.). To control both cover crop growth and weeds, 2 herbicides (metribuzin and rimsulfuron) will be applied at different reduced rates (up to 13% and 14% of the highest permitted rates of these herbicides in tomato, respectively). The effects of these herbicide applications on the cover crops and weeds and the overall impacts of the system on weeds and tomato plants (yield and nutrient composition) will be monitored and measured. A major challenge that will be addressed is minimizing interference caused by living mulches during harvest. From a preliminary trial in 2014, we observed several low-rate herbicide treatment plots with copious cover crop biomass production, low weed presence and tomato yields that were comparable or better than the hand-weeded, weed free check.
Project objectives from proposal:
The broad goal of this project is to evaluate cover crop species and herbicide management regimes suitable for inter-seeded cover cropping in vegetables of the Northeastern United States, which will facilitate their adoption and contribute to the sustainability of the agro-ecosystem. The hypothesis is that, when inter-seeded in wide-row vegetables, the chosen cover crop species and the herbicide techniques employed for management of the system will have no adverse effect on the vegetable crop, will yield substantial soil cover and cover crop biomass and will provide adequate weed suppression. The specific objectives are:
1. To study the effects of different herbicides and (reduced) rates of application on sole cover crop stands, measured in terms of cover crop recovery times and reductions in biomass, plant height, ground cover and stand density and to study the effects of the different herbicide- cover crop combinations on weed presence, measured in terms of biomass reduction and ground cover. This sole cover crop trial will test herbicides that are not registered for use in tomato, the vegetable crop in the trials.
2. To study the effects of treatments (chiefly, cover crop-cash crop competition and weed pressure) on the vegetable crop, measured in terms of vegetable yield and leaf tissue analysis (for nutrients). The most important factor for adoption, absence of adverse effects on vegetable yield would be suggestive of effective curbing of both weeds and cover crop-cash crop competition.
3. To study the effects of herbicide treatments on inter-seeded cover crop performance, measured in terms of reductions in biomass production, plant height, ground cover and stand density.
4. To study the effects of treatments on weeds, measured in terms of weed biomass and ground cover and kinds of weeds affected. Inter-seeding of cover crops presents opportunities to use lower-than-recommended rates of herbicides. Assessment of the weed presence in different treatment plots will demonstrate if such a reduction is feasible.
5. To study cover crop performance, measured in terms of biomass production, extent and duration of ground cover, stand density, plant height and nutrient composition of plant tissue. Cover crop performance being the major contributor to the sustainability functions of the system, maximization of biomass and ground cover enhances soil and overall agro-ecosystem sustainability.