Q.what is happening to my pine trees?
How can I stop this? The needles on my pine trees are turning brown in the middle. This is happening on all 5 of them.
There are a number of fungal diseases that might cause this: https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-browning.htm
Sometimes these conditions can be treated with fungicides https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
or by improving the soil drainage.
At this point it is important for you to get an identification of the disease, because some conditions are untreatable and require the removal of the trees to prevent spread of infection. Your local extension service will be glad to help you. This link will help you locate the nearest one:
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm