I just finished weeding my raspberry patch. I noticed that the leaves are turning yellow and some of the canes that were budding have died. I want to fertilize and bring this patch back. It has been going since 1970. I have added plants and have thinned them, the deer or something is eating off the tops of the sticks. what can it be??? and could this be the cause of the yellowing? or do I just need to water now that the weeds are gone...??? thanks for your help..