The Role of Preharvest Natural Infection and Toxin Contamination in Food and Feed Safety in Maize, South-East Hungary, 2014–2021

Abstract

Mycotoxins originating in the preharvest period represent a less studied research problem, even though they are of the utmost practical significance in maize production, determining marketability (within EU limits), and storage ability, competitiveness, and profit rate. In this study, 18–23 commercial hybrids were tested between 2014 and 2021. Natural infection from Fusarium spp. was higher than 1.5%, and for Aspergillus spp. this was normally 0.01% or 0, much lower than would be considered as severe infection. In spite of this, many hybrids provided far higher toxin contamination than regulations allow. The maximum preharvest aflatoxin B1 was in 2020 (at 2286 μg/kg), and, in several cases, the value was higher than 1000 μg/kg. The hybrid differences were large. In Hungary, the presence of field-originated aflatoxin B1 was continuous, with three AFB1 epidemics in the 8 years. The highest DON contamination was in 2014 (at 27 mg/kg), and a detectable DON level was found in every hybrid. FUMB1+B2 were the highest in 2014 (at 45.78 mg/kg). At these low infection levels, correlations between visual symptoms and toxin contaminations were mostly non-significant, so it is not feasible to draw a conclusion about toxin contamination from ear rot coverage alone. The toxin contamination of hybrids for a percentage of visual infection is highly variable, and only toxin data can decide about food safety. Hybrids with no visual symptoms and high AFB1 contamination were also identified. Preharvest control, including breeding and variety registration, is therefore of the utmost importance to all three pathogens. Even natural ear rot and toxin data do not prove differences in resistance, so a high ear rot or toxin contamination level should be considered as a risk factor for hybrids. The toxin control of freshly harvested grain is vital for separating healthy and contaminated lots. In addition, proper growing and storage conditions must be ensured to protect the feed safety of the grain.

Food Safety Aspects of Breeding Maize to Multi-Resistance against the Major (Fusarium graminearum, F. verticillioides, Aspergillus flavus) and Minor Toxigenic Fungi (Fusarium spp.) as Well as to Toxin Accumulation, Trends, and Solutions—A Review

“…Compared to preharvest problems, storage problems can be resolved much easier; however, without excellent preharvest control, the prevention of toxin contamination in the storage facilities is a nearly hopeless task. In an eight-year period, we found three aflatoxin years, with 2022 being the fourth such year [51]. As such, it is clear that, in Hungary, preharvest-origin aflatoxin contamination is present by up to more than 2000 mg/kg and strongly differs between hybrids.…”

“…As breeders concentrate on yielding ability, the resistance background of the hybrids remains mostly in shadow. A vast majority of the tested international hybrids are susceptible or highly susceptible to one or more major toxigenic fungi [10,[50][51][52]. This is proof that this is not the central problem of the maize breeding.…”

“…We recorded fumonisins in two investigated years (2014 and 2021), while in 2022, there was also a large presence of fumonisin. A significant amount of DON was recorded in three years, while, in 2022, no significant preharvest DON contamination was found, and only two years were without significant DON, fumonisin, and aflatoxin production across hybrids [51]. These data refer to the means in hybrids and, so, in years with lower mean levels, several hybrids may have still surpassed the relevant limit values.…”

“…AFB1, fumonisin, and DON contents strongly respond to increasing temperatures and drought conditions [1,61,62], and the combination of warm weather and higher precipitation favors DON-producing fungi, as well as many other toxigenic fungi, leading to high toxin accumulation rates [10,51]. Toxin forecasts are based on meteorological factors [9], with a 2.5 • C increase in temperature for the vegetative period throughout the whole Carpathian Basin, Lower Austria, and South Germany, as well as a 5 • C increase for Helsinki, potentially threatening higher aflatoxin contamination rates.…”

“…We speak about possibilities for the 10-15-year horizon, and the forecasts seem to otherwise be fair. Earlier in Hungary, there were not any problems with aflatoxin, unlike the situation at present [51,59]. Very large maize-producing areas are now under toxin pressure now, like the Mediterranean, Africa, Southeast USA, and South Asia, which are presently facing significant problems, and thus need help as soon as possible.…”