Melons turning yellow?

[catgirl]

Hi everyone,

I'm growing Galia melons for the first time in my greenhouse, and the plants so far have been brilliant, producing masses of flowers and now starting to produce fruit as well. On one of the plants, three female flowers opened and were hand-pollinated around the same time; I then pinched out the shoots with the fruit on them to encourage the plant to focus on growing the fruit.

This seemed to have worked quite well as I now have one melon which must be nearly 10cm in diameter. One of the others is still small (but it was the last to flower, so I'm not overly worried about that) but the other one started growing really well, but now suddenly has turned bright yellow. The other female flowers on the plant are turning yellow as well before they even open up.

Does anyone know what is going wrong here? The plants sit in large containers and are fed every couple of weeks - should I be feeding them more often? They are well watered and I can't see any pests on the plants. Do melons in containers and in this climate usually only produce one or two fruits per plant perhaps?

[WendyC]

Look on the underside of the leaves, perhaps with a magnifying glass. Are there any tiny mites on there, sometimes with a webbing over the leaf. That's red spider mite.
Is the whole plant yellow or just some leaves. A picture would help.

[catgirl]

Actually I have seen what I think is red spider mite - at least, they were very small, bright red and looked like spiders! I treated all the plants with a bug clear mixture a couple of times and haven't seen any since.

The leaves are actually all still green, it's only the flowers and fruit that are turning yellow. This is the worst one (top right corner, with the healthy big melon in bottom left):


And the little flowers that are forming are yellow as well, though it might be a bit hard to see. They were always green before, and still are on the other plants.


And when you compare that plant to the others, it just doesn't look as healthy! The others all look pretty much like this:

[BertieFox]

The fruit sounds like it is turning yellow as at this point the plant can't support them all, rather like courgettes that do the same thing at this time of year. I think there is a great deal to be said in allowing the plant build up to a good size with plenty of green vegetation before allowing the melons to set. Yellow fruit which then falls off is also a sign of unpollinated or poorly pollinated flowers.