Narcissus Bulb Fly - Merodon
Tue, 30 Oct 2007 11:44:30 PDT
On 30 Oct 07, at 9:00, James Waddick wrote:

> 	Can't say I have ever seen one here. Obviously Arnold has it 
> in New Jersey and Roger in British Columbia. How serious is it 
> elsewhere?
> 	Anyone else in the midwest have this problem?

If the collective readership will bear with another "I seem to 
recall" message...

ISTR that the agricultural authorities think that the narcissus bulb 
fly is rare in the US, but in fact it is fairly common.

Infestations may be quite localized, however. A bulb-loving friend 
here built a house in an outlying semi-rural wooded area and for many 
years enjoyed a narcissus-fly-free garden. A new house was built 
across the road and its owners brought along their old garden, 
including quantities of narcissus, and now my friend has to deal with 
these destructive pests.

The n.b.f. species are easily recognized: they burrow into the heart 
of the bulb via the basal plate, then gradually eat the bulb's 
interior out filling the space with reddish brown feculence. The 
grubs of the larger species are similar in appearance to those of the 
Japanese beetle, but somewhat smaller. (Memory may fail me here -- I 
haven't seen a Japanese beetle grub in 40+ years.) Moreover, there is 
usually -- not invariably -- only one grub per bulb. The grubs of the 
lesser bulb fly are quite small, about the size of a grain of rice, 
and usually there are a number of them in a single infested bulb.

Those of you currently free of n.b.f. can preserve your elite status 
by taking hygienic precautions: soak all newly acquired 
Amaryllidaceae in an insecticide solution; it will penetrate into the 
bulb and kill the grubs. Also be alert for signs of an infestation: 
infested bulbs often feel slightly soft, not hard and firm. And there 
is often a visible wound in the basal plate.

If you have a valuable bulb that you think may be infested but are 
uncertain, slice the bulb open with a sharp knife. An infested bulb 
is immediately obvious.

If it is uninfested, dust the cut surfaces with sulfur and plant it; 
you may lose flowers for a while, but it will recover. If it is 
infested, throw it away. It's very hard to salvage a bulb that's been 
seriously damaged by the bulb fly. If you are determined to attempt 
salvage, I would suggest first cleansing the interior of the feculent 
material (meanwhile removing and killing any grubs), then soak the 
bulb in a mild antiseptic to slow down bacterial decay. A good 
dusting with sulfur and potting up in pure washed sand may lead to 
active growth in the spring.

I was once in a nursery and noticed a pot of crinum that had been 
attacked by the bulb fly. The price was a bit stiff, but I was able 
to count 10 growing points; divided by 10, the price was quite 
reasonable. Bought it, brought it home, and planted each growing 
fragment spearately, and all survived, flowering to this day. 
Regrettably, it's a rather dull and uninteresting crinum.

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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