Were these plants new (from outside source )or related runners from previous crop? Would have heavily fed with FYM-3" layer prior to planting. Any signs of root pests?, wireworm? chafer grubs?,leatherjackets? Excavate a sample area and sieve to locate these.
If the remaining are valued, give a top dressing of hoof and horn, bonemeal and dried blood or similar to a section and compare with an untreated control section.Otherwise start again on previously uncropped area (with strawberries) and keep fingers crossed
Thanks for reply. I think they were a mixture of plants really. I usually grow new plants from healthy runners, but didnt have enough so bought in new to fill gaps (mail order bare root). may also have been a couple of slightly older plants transplanted from the old bed as they were still young enough to be productive. naughty i know but i have done it before with no problem, in fact they might be the only ones to have done OK in the current bed!
Havent checked for pests in the soil. Will look but dont normall have much problem with soil borne pests in the garden, thanks in part to a healthy bird population (blackbirds particularly).
I am thinking that starting again is the best option. I dont think the current plants are going to do any good even with generous feeding and mulching (I have recently given them some rose food to try and boost them, but not holding my breath). Bit limited for new sites so might end up digging out the soil from the problem bed and putting in fresh before replanting.
Whilst i am happy to start again it would be nice to know what caused the problem in the first place, so that i can try and avoid it happening again.