Re: Oranges and some other fruit.

Richard Lovejoy wrote:
> Now that I seem to be ?back into the fold? and thank you to all who
> responded I have a question(s).
>
> Earlier in the year when our oranges (Navel), tangerines and grapefruits
> were forming many of the fruits, around the fruit stems, started to show
> a white ?fungus? which looked powdery but when touched it was more
> sticky than powdery. On pointing it out to our gardener he promptly
> sprayed the trees and the problem diminished. However, residue was left
> and now when the fruit are well formed and we should be looking forward
> to enjoying the rewards in the coming weeks/months the fruit is falling
> from the trees. Clearly, the earlier ?fungus? is still evident in
> varying degrees on each fruit around the stalk point.
>
> Presumably, all this could have been avoided if the trees had been
> sprayed earlier. My questions are, do any of you knowledgeable folk know
> what this ?fungus? is, when should spraying have be done and with what?

Richard
From your description I should say that it is almost certain that the
orange problem is caused not by a fungus but by an infestation of
mealybug. These bugs, which will have been helping themselves to the sap
which should have been nourishing your fruits, drying them up and probably
causing their premature drop, are mobile creatures which protect themselves with a covering of loose powdery plates of wax distinctly sticky to the touch.

I wonder what your gardener sprayed with. If he thought it was fungus
what he used would have had no useful effect, but even if he knew they
were mealybugs he was dealing with it does seem as though he either picked an incorrect treatment or maybe he did the right thing but was not thorough enough..

Because of their protective waxy covering these insects are not the easiest to deal to. If only a few are involved (as for instance on a potted plant)it is quite common to use a cotton bud (a piece fo cotton wool on a stick) to apply a dab of methylated spirits or rubbing alcohol, but for large numbers this would be far too tedious and the usual treatment is an overspray of light horticultural oil in a continuous film, which simply excludes all air and smothers them. It may be difficult to catch every insect with the first application and it is usually wise to repeat the application after about two weeks to mop up any stragglers.

In the meantime you would be wise to exercise strict hygiene, picking up fruit which falls off as soon as it is seen and disposing of it so any mealybugs it carries cannot get back on to the trees. You could also check if the infestation is wholly confined to the fruit or whether it extends to some of the twigs. Odd colonies on these could probably be dealt with by dabbing with methylated spirits.

> Lastly, can anyone recommend a book(s) that is explicit in such matters
> that would help me in the future with any other problems concerning
> fruit, including plums and persimmon?

I think I should leave this to European list members. Because I live in an isolated country in the southern hemisphere the books I use here would not be the most helpful for you.
>
> Thanks
>
>
> Richard Lovejoy (Algarve, Portugal)
>
>
>


--
Tony & Moira Ryan,
Wainuiomata, North Island, NZ.     Pictures of our garden at:-
http://mywebpages.comcast.net/cherie1/Garden/TonyandMoira/index.htm
NEW PICTURES ADDED 4/Feb/2004


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