Sydney NSW, Australia
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Source: Agriland [summ. Mod.DHA, edited]

Wheat crops are under severe septoria pressure in some areas of Northern Ireland. Growers will have an opportunity to get a T1 spray on over the coming days and they must take it.

The very wet conditions during March 2023 encouraged a lot of the disease-related issues that are apparent now. With ground conditions so poor at the time, many farmers failed to get a T0 spray onto crops.

Wheat crops are currently falling into two categories. Those planted in September and early October 2022 are looking well. Those planted in mid-December 2022 and early January 2023 need a lot of growth to catch up.

[Byline: Richard Halleron]

Communicated by:

[Septoria leaf blotch of cereals is caused by fungi in the septoria species complex, which includes _Zymoseptoria tritici_ (previously _Septoria tritici_), _Mycosphaerella graminicola_ and _Phaeosphaeria nodorum_ (previously _Stagonospora nodorum_). They affect mainly wheat, but also barley, oats, and occasionally rye, as well as some grass species. Symptoms on wheat and barley are very similar, they may occur at any time during the growth cycle and on any portion of the plant. They include blotches on both leaves and glumes which reduce the photosynthetic ability of the host. Disease development is favoured by humid conditions. Up to 50 percent yield losses have been reported on susceptible varieties.

Spores can be spread by infected plant material, wind, water (rain splash), and mechanical means. The pathogens can overwinter on crop debris and on autumn sown crops or volunteers. Disease management includes fungicide treatments aimed at preventing the disease from becoming established on the upper 3 leaves of the crop canopy (where it would affect the ears most), removal of inoculum sources, and use of resistant varieties.

After the cereal rusts, septoria is considered the most important challenge to plant breeders (see ProMED post 20120831.1274190) and a threat to food security worldwide. Rotating or mixing chemical classes of fungicides is vital to extend the useful life of host resistance genes in crop varieties.

Pathogen strains with high levels of resistance to many fungicides are emerging in different regions (e.g. ProMED posts 20210809.8579912, 20160516.4225677, 20161031.4598540). Furthermore, the number of fungicides available for septoria control has been decreasing due to the withdrawal of products for environmental reasons (e.g. ProMED post 20210223.8207530). In addition to fungicide resistant pathogen strains, host resistance breaking strains are being observed in recent years (e.g. ProMED posts 20210721.8533591, 20190218.6322156).

UK:,,197, and (with counties)

Septoria symptoms on wheat:,, and
Septoria diseases and pathogens, photo gallery:

Information on septoria diseases:,,,,,, and
Taxonomy of fungal species via:
- Mod.DHA]


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