Organic production is one of the fastest growing food sectors globally. However, average yield in organic vegetable production is up to 33% lower than in conventional production. This difference could be due to higher fertilization rates in conventional, compared to organic, farming. We aimed to compare yield and quality characteristics of carrots produced under equal nitrogen fertilization rates over four years in organic and conventional conditions. We found a 14.5% higher marketable, and 10.0% lower discarded, yield in the organic compared to the average conventional treatments. In addition, carrots managed organically had 14.1% lower nitrate and 10.0% higher vitamin C content than carrots managed conventionally. There were no convincing effects of cultivation system on the nitrogen, total sugar, or dry matter content of carrots. Organically managed carrots were free of pesticide residues, while several residues were found in carrots managed conventionally. Our study reveals that organic management of carrots may exceed that of conventional methods in yield and several quality characteristics, while being free of pesticide residues. Organic fertilizer gave an advantage over mineral fertilizer, when equal rates of nitrogen were used in both production systems.

The increase in the cultivation area of cruciferous oilseed crops and the use of short crop rotation has resulted in the enhanced spread of several major pests in Northern latitudes. There is currently limited information about incidence and severity of Alternaria black spot disease (Alternaria brassicae) on the main oilseed crop, spring oilseed rape (Brassica napus), in the Northern Baltics. Thus, spring oilseed rape and five alternative cruciferous oilseed crops were selected and their resistance to black spot disease was evaluated in field conditions during two growing seasons. We hypothesized that spring oilseed rape is more susceptible to Alternaria black spot disease than other alternative cruciferous oilseed crops. Both growing seasons were warmer and drier compared to the long-term average, and were thus suitable for A. brassicae development and assessments. In both years, incidence of Alternaria black spot infection was recorded on all cruciferous species, yet the disease development differed considerably among the crops. During both growing seasons, black mustard (B. nigra) plants were the most infected. Based on our observations during warm growing seasons we conclude that alternative oilseed crops such as Sinapis alba, Eruca sativa and Raphanus sativus are more resistant to the Alternaria black spot infection than the traditional oilseed crops and thus, possess a great potential to grow with limited chemical disease control in Northern Baltic conditions.

The pathogen Erysiphe cruciferarum is an increasingly serious threat to cruciferous oilseed crops worldwide. In the present study, the severity of powdery mildew was evaluated on spring oilseed rape (Brassica napus) and five alternative oilseed crop species (B. juncea, B. nigra, Sinapis alba, Raphanus sativus, Eruca sativa). The main aim of the study was to identify plant species that are less susceptible to powdery mildew for possible application as cover crop, in trap cropping or seed production. Powdery mildew assessments were conducted in two growing seasons that were characterised by unusually warm and dry conditions for northern temperate climatic conditions. In both growing seasons, a heavy powdery mildew infection (over 80%) was recorded on B. napus and B. nigra plants, indicating that E. cruciferarum is an important pathogen for oilseed crops in northern Baltics. However, three other cruciferous species S. alba, E. sativa and R. sativus showed full resistance to powdery mildew, and thus, even under strong powdery mildew pressure, they can be cultivated without pesticide application in northern Baltic conditions. We suggest that in changing climatic conditions powdery mildew is expected to become a more serious problem in cruciferous oilseed crops in northern Europe, especially under intensive short-rotation farming practices.

For centuries barley has been an important food crop for mankind. It is important to produce crops that are of good quality and safe to human and animal organisms. However, pathogenic fungi in cereals cause health problems both to humans and animals. In Estonia the microbiological quality of cereals has been studied to identify Fusarium species in feed cereals. Still, the relationship between the agro-ecological conditions and the total abundance of moulds and yeasts on grain has been studied little in Estonia. In 2009 and 2010, we carried out field trials in the experimental station of the Estonian Research Institute of Agriculture in North Estonia (59°18'N, 24°39'E) and in the experimental station of Olustvere School of Service and Rural Economics in Central Estonia (58°33 'N, 25°34'E). The variants of the experiment were barley in pure crops with added ammonium nitrate 120 kgN ha^–1, barley in pure crops with added ammonium nitrate 60 kgN ha^–1, barley in pure crops with no added ammonium nitrate, and barley–pea mixed crop. After harvesting, the grain was dried to 14% of moisture and grain samples were taken from each trial variant. The abundance of moulds, yeasts, and Fusarium spp. was determined in grain samples using the dilution method. The impact of the levels of nitrogen, location of the trial site, and year (weather conditions) on the abundance of moulds, yeasts, and Fusarium spp. was studied. The common genera of moulds identified were Cladosporium, Acremonium, and Fusarium. According to our results, yeasts were the most common fungi on barley grains. In North Estonia the abundance of moulds was lower compared to Central Estonia. The abundance of fungi was not affected by different levels of nitrogen or whether barley had been grown as a pure crop or a barley–pea mix. The weather conditions had the greatest impact on the abundance of microfungi.