How far away from tomatoes can I plant blackberries?

Question

I'm a novice gardener. When researching various vegetables/fruit to plant, I keep finding commentary not to plant X crop where Y has grown.

For a specific example, this article talking about how blackberries shouldn't be planted near nightshade crops (tomatoes, peppers, etc):

Also avoid planting where any nightshade family members - tomatoes, potatoes, eggplants, peppers - grew in the last 2 years, as they can transmit verticillium wilt to blackberry plants.

I started my garden this year, with a raised bed, new soil growing tomatoes/peppers. I have room to put in another raised bed separate for the blackberries, but they'd be within 8'-10'.

Is this speaking specifically in the same soil, or a certain distance?

Answer 1

Verticillium is a fungus disease of plants which can exist in a dormant form in soil for many years (much longer than two years).

It doesn't spread by any other method except direct contamination. If you work with dirty tools or wearing muddy boots, you can transfer it just as effectively over a distance of 8 feet or 80 miles.

On the other hand, there is no sense in getting paranoia about every possible plant disease you read about on the web. You might consider the UK Royal Horticultural Society statistics for the disease: the two most common species affected were trees, Acers (213 reports) and Cotinus (113). At the other end of the scale, there were a total of six reports for solanum species, and just three for blackberries.

Provided you keep your garden reasonably "clean and tidy", the likelihood is that you will never have problems with verticillium at all.

The most important consideration on where to plant crops is to rotate them, so you don't grow the same species in the same place for year after year. Obviously you can't do that for blackberries, where the same plants will produce fruit for many years, but if you grow your solanum species in the same place every year you will increase the risk of disease - but not necessarily verticillium.

Answer 2

My answer is just based on limited experience (so you might defer to others for more than anecdotes).

In my semi-arid climate, in 2018, I grew tomatoes with only a path (maybe three feet wide) separating it from our thornless blackberries (which blackberries had been there for many years). The tomatoes did not contract any diseases from the blackberries, nor vice versa. They're such different plants in their growth habits that I wouldn't expect people would normally plant them close enough to each other for it to matter. It's possible that it would be a bigger issue in a humid climate where fungal diseases are more of a problem. Our blackberries and tomatoes were just directly in the ground.

In 2019, I had a few tomatoes at about the same distance from the blackberries, with no issues. One of the tomatoes actually was diseased, probably with some kind of Alternaria (but the disease came with it from the store, and didn't seem to bother the blackberries, although it did spread to some other tomatoes a fair distance away). The tomato wasn't bothered terribly by the disease (but I could tell it had one).

In 2020, this year, I have tomatoes probably about 15 feet from the blackberries. They all seem healthy enough. Ditto for 2016, and 2017.

Now strawberries, on the other hand, I planted a tomato (Tidy Rose F1) in the middle of a strawberry patch (the ground was mulched, too), and it got severely diseased and died (while the tomatoes further away, which were not with strawberries, did not get that disease).

We had potatoes on the other side of the path from the blackberries, this year. The potatoes did not do well (they looked diseased to me, although we harvested and ate them), but the blackberries were fine.

Anyway, it might be wise to be careful and not put them super close, but I wouldn't bother extending lots of effort putting them zillions of feet away.

I had never heard before about keeping nightshades and blackberries separate. I had heard about keeping blackberries and raspberries separate, though.