Watermelon disease

[Sim2500]

Watermelon yellow flesh variety called champagne. Its grown in a green house and has been doing well until recently

Any thoughts?

https://imgur.com/a/JQmloTK

[ameno]

It's alternaria leaf blight. It's a fungal disease all cucurbits can get. It has becomes very common on my allotment in the last two years.

Generally speaking it will only affect the leaves (although I did get one infected melon fruit last year, and sometimes it will also infect and kill thinner stems)), but it can cause complete defoliation, which will kill the plant. It seems to thrive in hotter, drier conditions.

I would remove the worst affected leaves, and keep the plant well fed and watered in the hope that it will grow out of it (or at least the fruits ripen before the plant dies).
The fungus will not survive in the soil or the compost heap, so it is safe to compost or bury the material. However it will survive the winter on surface crop waste, so don't leave dead leaves and stems lying around over winter, or it will come back quicker next year.
I say "quicker" because alternaria fungi are very common. They are everywhere and have many common weeds as hosts, too. So chances are you will get it again next year regardless of what you do to prevent it, it's just a difference of when you get it and how severe the infection is.

[Sim2500]

It's alternaria leaf blight. It's a fungal disease all cucurbits can get. It has becomes very common on my allotment in the last two years.

Generally speaking it will only affect the leaves (although I did get one infected melon fruit last year, and sometimes it will also infect and kill thinner stems)), but it can cause complete defoliation, which will kill the plant. It seems to thrive in hotter, drier conditions.

I would remove the worst affected leaves, and keep the plant well fed and watered in the hope that it will grow out of it (or at least the fruits ripen before the plant dies).
The fungus will not survive in the soil or the compost heap, so it is safe to compost or bury the material. However it will survive the winter on surface crop waste, so don't leave dead leaves and stems lying around over winter, or it will come back quicker next year.
I say "quicker" because alternaria fungi are very common. They are everywhere and have many common weeds as hosts, too. So chances are you will get it again next year regardless of what you do to prevent it, it's just a difference of when you get it and how severe the infection is.

Thanks for the advice. The older leaves see the worst so I'll prune them off and destroy. I've so bought some copper fungicide and literature says that can help.

It's almost harvest time for the water melon as I can see the tendril turning almost all brown so another week.

[ameno]

Copper fungicide has been outlawed for use by amateurs (possibly even by farmers, too) in the UK. Indeed, you can't really by any fungicides in the UK anymore which can be used on vegetable crops.

Also, with most fungal diseases fungicides are sadly more protective that curative. Using them before the plant becomes infected will help prevent infection, but they have limited effect one infection has actually taken hold.

if the fruit are already nearly ripe, though, I wouldn't worry too much. If you keep removing the badly affected leaves then the plant should last at least another month yet, maybe more. Plenty of time for the fruit to ripen.

[Jungle Jane]

I wouldn’t use any chemical now so close to harvest. Melon leaves do look a state at this time of year,feed with a high potassium fertiliser. How is the melon,they’ve done well this year,it’s not usually this sunny

[Sim2500]

Copper fungicide has been outlawed for use by amateurs (possibly even by farmers, too) in the UK. Indeed, you can't really by any fungicides in the UK anymore which can be used on vegetable crops.

Also, with most fungal diseases fungicides are sadly more protective that curative. Using them before the plant becomes infected will help prevent infection, but they have limited effect one infection has actually taken hold.

if the fruit are already nearly ripe, though, I wouldn't worry too much. If you keep removing the badly affected leaves then the plant should last at least another month yet, maybe more. Plenty of time for the fruit to ripen.

That's interesting because I managed to buy a product on amazon called bonide copper fungicide but its basically copper soap.

You and another user are probably right about not using any chemicals so close to harvest. Atleast next season I know what to expect