Grain Harvesting Strategies to Minimize Grain Quality Losses Due to Fusarium Head Blight in Wheat

Abstract

Fusarium head blight (FHB) reduces wheat grain yield and quality, leading to price discounts due to Fusarium-damaged kernels (FDK), deoxynivalenol (DON) contamination of grain, and reduced test weight (weight per unit volume of grain). Experiments were conducted to determine whether changing combine harvester configurations to differentially remove diseased kernels affected the yield and quality of grain harvested from plots with different mean levels of FHB index (IND, mean proportion of diseased spikelets per spike), achieved with inoculations at different spore densities. Plots were harvested using four combine configurations, with C1 being the standard, set at a fan speed of 1,375 rpm and a shutter opening of 70 mm, and C2, C3, and C4 regulated to fan speeds and shutter openings of 1,475 rpm and 70 mm, 1,475 rpm and 90 mm, and 1,375 rpm and 90 mm, respectively. C3 and C4 consistently had significantly lower mean arcsine-transformed FDK and log-transformed DON and higher mean test weight than did C1. However, C3 and C4 also resulted in significantly lower mean amounts of harvested grain than did C1. The estimated mean responses to combine configuration were consistent across a range of mean IND levels (5 to 35%). Using a common price discount schedule based on the incidence of FDK, DON, and test weight, and the mean values found in the current investigation for these grain-quality variables, configurations C2, C3, and C4 resulted in between $10 and 40/t lower estimated grain price discounts than C1, with the lowest discounts corresponding to C3 and C4. Using the discount values, a range of grain prices, and the mean yield values from this investigation, estimated gross cash income (GCI; mean estimated yield × grain price adjusted for discounts due to inferior quality) was generally higher for grain harvested with C2 and C4 than with C1 or C3, with C4 being the most consistent across a range of IND levels (5 to 35%) and grain prices ($118 to 276/t). For all modified configurations, the greatest increases in GCI over C1 were observed at the lowest tested grain price, and the improvement of GCI over C1 increased with increasing IND up to the highest disease level tested. Thus, these results showed that, when harvesting grain from FHB-affected fields, the improvement in grain quality and reduction in price discounts with a combine adjustment could be great enough to counteract the reduction in harvested grain that results from the adjustment.

Study on Prevalence of Mycoflora in Wheat Seeds

“…According to Duveiller and Gilchrist (1994), Salgado et al (2011) and Wiese (1987), the most important seed borne fungal diseases of wheat were Helminthosporium leaf blight (caused by Bipolaris sorokiniana and Pyrenophora triticirepentis), Fusarium head blight (incited by Fusarium spp.) and Black point/smudge (caused by Alternaria, Fusarium, Cochliobolus, Aspergillus, Cladosporium, Penicillium, Rhizopus and Stemphylium).…”

Agressividade diferencial de espécies do complexo Fusarium graminearum em interação com o fungicida tebuconazole na redução do rendimento de trigo

“…Fungicidas do grupo dos triazóis, que possuem ação fungistática sobre F. graminearum sensu lato, têm sido indicados para uso durante o fl orescimento pleno (YIN et al, 2009). Considerando que grãos giberelados são menores e mais leves do que grãos sadios, especialmente aqueles infectados no início do fl orescimento, o ajuste dos mecanismos da colheita mecânica pode facilitar a eliminação de grãos giberelados e, consequentemente, reduzir os níveis de micotoxinas nos lotes de grãos colhidos (SALGADO et al, 2011). Além da extensão da janela de infecção que pode levar a menores danos em rendimento em infecções tardias (DEL PONTE et al, 2007;COWGER & ARRELANO, 2010), não se tem conhecimento se diferenças fenotípicas entre as espécies do complexo podem infl uenciar no rendimento e formação dos grãos.…”

Mycotoxins in Wheat and Mitigation Measures

“…Harvesting strategies, moisture, water activity (A w ), temperature, storage period, contamination rate, broken grains, insect presence, and oxygen rate are the main critical points to manage in order to mitigate the mycotoxin risks postharvest [48,[50][51][52]99].…”

“…Management strategies during harvest include wheat harvest at low moisture or A w , reduced mechanical seed damage, and the use of different grain harvest strategies to remove diseased kernels which are often lighter than the healthy ones. The use different harvesting configurations, with varying fan speeds and shutter openings, resulted in lower Fusarium-damaged wheat kernels and DON content in harvested wheat [99,100]. The removal of damaged grain implies a loss in the yield of harvested grain, but results in better storage conditions and improvement in grain safety offsetting the economic losses.…”