No it's not a reasonable conclusion. Correlation does not lead to causation. If two variables are linked, then they may affect one another or there may be another set of factors involved. There isn't enough info to know for sure. The fact that r = -0.7 is fairly close to r = -1 indicates there's moderately strong negative correlation, but I don't think it's strong enough in my opinion. More research is needed.
In short, the keyword "caused" as part of the claim is what makes it unreasonable. There is no way to know that not eating vegetables leads to high blood pressure. It may be true but again, more info is needed.
