[wasthiswise]

Can anyone identify my rasp problem? I have 2 rows of autumn rasps side by side, and whilst one of these rows is fruiting well the other is a dead loss and producing nothing. It was like this last year too. The 'fruits' on the bad row appear to have never developed much beyond the flower stage and now look like brown dried up 'tiny' rasps - see photo. The leaves look healthy, the plants have grown vigorously and are about 5ft high and there is no sign of leaf spotting I can tell. They've been well looked after, with winter mulching and fertilizer in early spring. The rows are different types, the good one is Polka, the bad one Autumn Bliss I think. Anyone know what the problem is? Thanks.

[JayG]

Tricky - no obvious signs of virus infection from your pic, and it's pretty unlikely that one row would have been pollinated and the adjacent row hardly at all.

Raspberry clusters can look like that if you forget to pick them because they rapidly succumb to moulds when ripe, especially in damp weather, but I'm assuming the fruits didn't develop properly in the first place?

Autumn Bliss is a very popular and usually very reliable variety - although the rows are adjacent are your AB's seriously disadvantaged compared to the others when it comes to light levels, for instance?

How long have you had them? It is possible that despite appearances they do have a virus which is affecting their ability to fruit properly, although I would be surprised to find it had affected them that badly.

[wasthiswise]

The fruits on the AB never developed properly in the first place. This is the middle of 3 rows (2 autumn, the other summer). The 2 unaffected rows have been fine, with lots of fruit. The AB's have had none at all. Zero! The row is not really disadvantaged light wise, there was a 3ft gap between the rows before they starting growing this spring but the growth has been so vigorous in all rows that that gap is almost closed up. Even if some could have done with more light, which I doubt, that would not explain a totally absent crop.

I originally had all these rasps in a veg patch in my back garden, bought 5 years ago. But they never did well enough there [too shady] so 2 years ago I transferred them all to the allotment into beds which had been properly prepared by me [dug trench, added lots of manure etc] and now 2 of the rows are doing brilliantly but the AB a dead loss. Really strange.

Unless by magic something miraculous happens soon my inclination is, in November, to rip out the entire row taking care to remove all roots, then replant with Joan J - which I have on my other plot and which produces amazingly large fruit.

[JayG]

Only problem with that plan is that if the AB's are diseased it may transfer to the Joan J's if you plant them in the same place, although if they are plants you already have to hand at least the financial loss won't be great (especially if you can plant suckers from them and leave the plants where they are.)

[wasthiswise]

Well, one thing I forgot to mention is that there is 1 'foreigner' already in the row - an allgold that somehow I stuck in the middle of this row in error - and it is doing fine. The cost of buying 12 rasps then waiting a year to see if they suffer the same problem I'd say is worth the risk.

[gobs]

Does the middle row get dry?

I just think, it is unlikely it would be diseased and the rest  nearby wouldn't be. Even though viruses take some time to spread, I should think there would be some symptoms showing.

There is also such a thing as infertility... Honestly.  I'd be tempted just to replant them with spare canes and see what happens.

[gobs]

As a second thought, look out for insects, too. Is there an ant nest for example, farming aphids, under this row?

[wasthiswise]

No idea about ants nests - haven't delved too closely. Just seems v. odd that this problem seems to affect all those of a given variety in this row, yet neither of the other 2 adjacent rows. Which suggests a variety specific problem. If it were a nest it would not explain  it affecting the whole of a 20ft row yet neither row either side. All 3 rows were prepared and planted at the same time, using the same method and same manure etc. Somehow I doubt I'll discover the actual problem, just have to retry and if they fail, use the space to grow something other than rasps.