Forests
If red pine growth loss and death from Diplodia is not acceptable for your site, leave wildlife and seed trees other than red or jack pine in areas where you want to grow young red pine. Red pine within a distance at least twice the height of nearby mature red and jack pine are most at risk of infection. If there are only red and jack pine on the site, leave clumps of pines, rather than scattered pines, for wildlife and seeds. Diplodia often kills some red pine saplings and slows the growth of others growing close to older red and jack pines, but the level of impact varies enormously from site to site and year to year.
It will be more challenging to grow young red pine in settings other than clear-cuts. You may have success with planted or natural red pine in the middle of harvested gaps. Consider creating gap sizes of 3/4 acre or larger, since red pine is not very shade tolerant. In situations where Diplodia is abundant or causing severe disease, or other species are competing aggressively for light (regardless of the presence of Diplodia), only a few red pines may survive in gaps regardless of size.
If red pine seedlings and saplings are abundantly and vigorously growing under an overstory of red pine, and there is minimal competition with other plant species, that could indicate you might be able to naturally regenerate the stand. Work with a professional forester if you desire to do so.
Yard trees
A ponderosa pine planted in Minnesota with severe Diplodia shoot blight.
Shoot blight from Diplodia is common in the ornamental landscape but only becomes severe on non-native pines and stressed red and jack pines. Ponderosa and Austrian pines can be very susceptible to severe shoot blight, so we caution against planting them unless an ornamental tree expert can assure you they will do well.
Here is a list of ways to reduce shoot blight. Please see Diplodia shoot blight and canker for details.
Prune blighted shoots.
Water during droughts.
Do not fertilize unless a soil test suggests it is needed.
Ensure the soil pH is appropriate for the tree species.
Apply a fungicide registered for use against Diplodia and according to the fungicide directions. See details at Diplodia shoot blight and canker. Note that fungicides will not get rid of the current disease in the canopy and multiple applications per year are often required.