Effect of a Mustard Green Manure on Potato Yield and Disease Incidence in a Rainfed Environment

Abstract

The goal of this work was to evaluate the short‐term effects of a mustard green manure on potato yield and disease incidence for potatoes grown in a rainfed cropping system. Diseases of interest were black scurf (Rhizoctonia solani), powdery scab (Spongospora subterranea), and white mold (Sclerotinia sclerotiorum). On‐farm trials with large (60‐ft wide) replicated plots were established at three sites in 2003 and 2004, in Maine. Mustard (Sinapis alba and Brassica juncea blend) was sown at a seed rate of 10 lb/acre, mowed at late flowering, and then disked into the soil. In the following season, tuber yield was measured at each site and compared to that of potatoes grown in barley (Hordeum vulgare) check plots. Incidence of white mold on leaves and stems, and Rhizoctonia incidence on tubers, were evaluated at one site over two years. On average across all the sites, total tuber yield was 8% greater following mustard green manure versus barley. Mustard green manure was associated with decreased incidence of Rhizoctonia on tubers, and increased incidence of white mold on leaves and stems, in the following potato crop. No effect was observed on incidence of powdery scab.

Comparison of Soybean, Canola, and Mustard Meals as Organic Sources of Nitrogen for Potatoes in Northern New England

“…Data on incidence of common scab and Rhizoctonia were variable and did not show any significant treatment effects ( data not shown ). Previous work has shown that mustard green manure (not mustard seed meal) is associated with decreased incidence of Rhizoctonia, and in some cases with decreased incidence of common scab (9,18); however, in the current study using seed meals we did not observe a consistent effect on incidence of these diseases.…”

The Benefits of Crop Rotation Including Cereals and Green Manures on Potato Yield and Nitrogen Nutrition and Soil Properties

“…Data obtained in the present study are in accordance with previous investigations which showed that 2 or 3 yr cereal-potato rotations and GMs can reduce the occurrence of potato diseases, including black scurf [17,68,69] and common scab [16]. In the present study, the lowest incidence of black scurf and common scab was recorded for potato grown after summer GMs (mustard, japanese millet, and pearl millet).…”

“…In the present study, the lowest incidence of black scurf and common scab was recorded for potato grown after summer GMs (mustard, japanese millet, and pearl millet). The suppressive effects of these green manure crops on potato black scurf and/or common scab have been demonstrated in various studies reporting the control of potato diseases with pearl millet [70], japanese millet [68], and mustard [15,17]. As shown in the present study, these green manures also increased soil microbial activity (Table 6) which may result in increased competition for existing nutrients [18,71] or increased populations of antagonistic organisms against S. scabies [71,72] or R. solani [15].…”

“…The suppressive effects of mustard and other Brassica spp. are often attributed to their high contents in glucosinolates [15][16][17]. Cereals used in the present study included barley, corn and oat which have been recognized to suppress potato diseases [73].…”

“…Crop rotations including GMs may also enhance potato yields and quality by breaking the cycle of weeds, pests, and diseases, although their action mechanisms are varied and often unknown [16]. Brassica species are often considered the most effective to suppress soil-borne diseases, likely because of their high contents in glucosinolates which breakdown in toxic compounds such as isothiocyanates [14,17]. Incorporation of GMs may also stimulate other microorganisms that help biological control of potato diseases through competition [16,18].…”