I've heard that the nightshade family can be a problem for raspberries. Can I plant eggplant near my raspberries - how far away should I place my eggplants? My Raspberries are in a raised bed with a wood frame. Thank you, Carolyn
Thanks for your question about planting berries with nightshade plants. There are several blogs about this issue, and the only scientific article I can find is one that indicates that both raspberries and the nightshades are susceptible to verticillium wilt. This is a pathogen (fungus) that grows in the soil, and is especially troublesome in wet, poorly draining soil.
According to this article, "Verticillium Wilt of Raspberry,"
"Verticillium wilt is caused by the fungus, Verticillium alboatrum. It is a very common soilborne fungus, and has been reported to cause wilt on more than 160 different kinds of plants including strawberries, eggplant, tomatoes, potatoes, stone fruits and peppers."
One of the structural differences between the raspberry cane and the nightshade plants is that the canes are perennial (they continue living and producing fruit throughout the years), but the nightshade vegetables are annual (they produce their flowers, fruits and seeds in one growing season, and then die.) So, you can select entirely different environments that are beneficial to the two types.
I can't find any research indicating distance to keep them from each other, but one article indicates the verticillium pathogen is in the soil from 12 to 16 inches deep. If it can spread that deep, arguably, it can spread that wide as well, but I can find no authority for that.
But, discretion being the better part of valor, suggest you keep them at least 3 feet away from each other. And, remember, you'll want to plant the raspberry in a spot you intend to leave them permanently. Don't plant the nightshades uphill from the raspberries, lest the water drains down, potentially carrying the fungus with it.
Hope this is helpful. Good luck!