Research crack butts this year with 28 varieties

In both 2017 and 2018, extensive research was conducted into 'crack holes' in sowing onions. A variety effect or negative influence of herbicides could not be demonstrated in either year. This year the research will continue with 28 varieties and the latest herbicides will be included in the research.

As far as is known, the cracks are the result of regrowth after a period of stagnant growth due to heat stress. The stagnant growth results in cracking and corking of the basal plate near the root crown. The symptoms correspond to those of too late or too abundant nitrogen application, in combination with too fast growth.

To avoid these cracks as much as possible, it is advisable to ensure good soil structure, homogeneous emergence and calm and even growth. Also use as few growth substances as possible.

Do herbicides affect cracks?
In practice, the assumption is that the use of herbicides may have a negative effect on crack roots. In 2017 and 2018, Colijnsplaat conducted 2 herbicide tests in sowing onions with various products in different dosages. The tests examined whether there was any effect on cracks.

The conclusion in both 2017 and 2018 was that no difference could be found in the degree of damage. The test will be repeated again this season, with the latest herbicides. If the test leads to the same conclusion as in 2017 and 2018, the influence of herbicides on promoting crack cracks can be excluded.

Possible race effect?
In addition to the possible influence of herbicides, a possible variety effect on the occurrence of crack spots was also examined in 2017 and 2018. More than 2 varieties were examined and assessed at 20 locations (Dronten and Colijnsplaat). The conclusion: no breed effect in either 2017 or 2018. This year, the research will be repeated at these 2 locations and even slightly expanded in terms of breeds; 28 varieties are examined and assessed. Here too, the question is whether the results of 2017 and 2018 will be confirmed.

This article is from Ureka† Uireka is a unique chain project, where Hazera participates in. Its aim is to improve the quality, and thereby strengthen the export position, of the Dutch onion.