2 Weather and Growth Development 2022

Managing Director (LD) Johann Portner, District Administrator Anton Lutz (LR), and Agricultural Distract Administrator Stefan Fuß (LAR)

The 2022 hop year began with a warm spell and with little precipitation in the Hallertau. At Hüll, the average February temperature of 3.9 °C was almost 5 °C warmer than the long-term average. March also broke a record with only 9.1 mm of precipitation. This meant that all spring field work on wires could be completed on schedule, on dry soil. In spite of the mild winter, however, an unusually cold April delayed budding in the hop gardens by about one week compared to the annual average. The training of the bines, therefore, started only in May. This year, height and width pruning had only a small effect on the developing plants, but there were significant differences between sites with north and south exposure, as well as between crops at different altitudes. A dry and warm spell in May accelerated plant growth, and crops quickly reached average height levels. Tillage could take place under optimal conditions, but in June, the effects of the drought became more and more noticeable. The first extended heat wave, reaching a maximum temperature of around 36 °C on June 19, caused additional difficulties for the crop’s development. The bines ended their vegetative growth prematurely and showed only weak side shoot formation in the upper bine and head area. At the same time, many stocks blossomed prematurely; and it did not help that July and August were dry and very hot, with extremely little precipitation. In some regions, monthly precipitation dropped to less than 20 mm. As a result, budding and side shoot development was below normal, and already near the end of July, the plants were so stressed that they delayed their normal cone formation. In some unfavorable sites, the plants shed their leaves and the cones remained very small.

Sufficient rainfalls around August 20 prevented an even worse situation. Landraces and other older cultivars suffered especially severely from the extreme weather. This resulted in significant losses in yield and quality, especially in terms of alpha acid content.

In the field of plant protection measures, 2022 differed significantly from the previous cool and damp year 2021. The dreaded pest, downy mildew (Peronospora), for instance, which thrives particularly well on wet leaves after a lot of precipitation, required only two interventions this growing season in plots with tolerant varieties, and only three interventions in plots with susceptible varieties, whereas the same pest required up to eight such interventions with much less effectiveness in 2021 Conversely, the dry and hot weather-loving common spider mite required much more vigilance this year. Already at the end of May, half of the hop yards in the monitoring program were already infested, with some plots showing infestation well above the intervention threshold. Likewise, hop aphids arrived extremely early and in full force already in mid-May. While hop aphid infestations can be controlled relatively easily with one or two protection measures, spider mites are more difficult to control and required repeated acaricide applications all the way up to the harvest.

The hop flea beetle too has become a rapidly increasing problem in recent years in spite of efforts to combat it. Adults surviving the winter start causing leaf damage even at the plant emergence stage, followed by additional damage from the next generation hatching in July, at which point the blossoms, cones, and shoots become part of the hop flea beetle diet. Severe infestations, therefore, can lead to significant damage. On the other hand, powdery mildew and Verticillium wilt, which caused severe sporadic losses in yield and quality in previous years, were less widespread in 2022, as a result of the weather.

The hot weather led to local, violent thunderstorms. On May 19, for instance, a hailstorm caused considerable damage in the center of the Hallertau. Since the hops had barely reached half the height of the trellis at this point, many hours of work were required to stimulate the regrowing of side shoots.

On June 20, a second devastating hailstorm with strong gusts of wind passed through the southern part of the Hallertau from the northwest to the southeast. Even though the hailstones were small, they caused enormous damage. Up to 2,000 ha of hop acreage were affected in various degrees, and crops were not harvested on several hundred hectares because the low yields would have made that uneconomical.

Overall, the 2022 crop year will go down in history as an extremely dry year with high yield losses, especially for landraces and older cultivars. On the other hand, newer cultivars with significantly more efficient root systems demonstrated their improved climate resilience. In locations where water supplies became completely exhausted, however, even these varieties reach their performance limits. The ability to irrigate hops has rarely been more economically significant than in 2022.

Table 2.1: Weather data for 2022 (monthly mean, maximum, and minimum values) compared to 10-year * and 30-year ** mean values

* The 10-year mean covers the years 2012-2021

** The 30-year mean covers the years 1961-1990