Introduction to Dothistroma Needle Blight

Dothistroma Needle Blight (DNB), previously known as Red Band Needle Blight, is a fungal disease of pine trees. The fungus has very occasionally been found on other conifers, but has only been a problem on pines. Because of this, currently this DNB reporting line only takes reports of the disease on pine trees.

DNB usually has an annual life-cycle, infecting this summer's newly-grown needles with spores ejected from fruitbodies on the needles that were infected the previous year.

DNB causes browning and loss of older needles, i.e. those needles that are further down the branch, not those at the branch tip. Current year's needles (i.e. those at the branch tips) will remain green until at least late summer and usually show no clear symptoms until they are almost a year old.

In the pages that follow you will be asked some detailed questions, not only about the pattern of damage on the tree as a whole, but also about the particular form of discolouration on the needles themselves. If you cannot provide this detail then you may find it useful to re-inspect the tree or trees about which you are concerned. Furthermore, the symptoms required for confirmation of Dothistroma Needle Blight are very rarely seen outside the summer months (April to September) and we recommend that you assess your tree(s) during June, July or August , as this is when the symptoms are most obvious.