I live in herefordshire and grow lots of onions on a well drained
limestone slope.For the last 20 years or so,I have grown the onions on
the same site,and although have lost a few plants with white rot,have
never had any problem with mildew-indeed most of the problem has been
that the soil has been too dry.However last year,which was a wet
summer,I had such a bad problem(with sets and transplants grown from
seed) that I pulled the onions very early to prevent the mildew going
into the bulbs and hence causing storage problems.
This year I have moved the onions to a different site-and planted the
sets much earlier(February 1st).This recent wet weather has brought in
mildew again.The sets are mainly fully grown and already falling
over(July 8th),but still have telltale signs of mildew on the
leaves.The transplants(set out at end of March)are beginning to bulb
up but also have mildew badly.I have sprayed all of the onions twice
now with a mixture of wettable sulphur (older books recommend flowers
of sulphur)and a copper oxychloride product(Fungex),and I will just
have to hope that this works to some extent.I had thought of using a
product containing mancozeb (Dithane 945),but the description on the
packet does not mention onions.
I am sure that many gardeners will be having problems with mildew.Does
anyone have a workable solution-perhaps spraying earlier,say in June
for example,before the mildew strikes.What do commercial growers use??
Or the organic gardeners??Also what is the best method for harvesting
to increase storage time??
Hope someone can help,as a bed of onions stricken with mildew is a
sorry site.
regards,Michael
P.s.I am not on or near an allotment site,and the only other gardener
growing vegetables is 400 yds away.