Is this mosaic virus?

[SteamedSprouts]

Hi,
I am growing pumpkins and have found that yellow patches have appeared on two of the plants, which can be seen in these photos:






The patch on the plant in the first photo appeared about a couple of weeks ago, and has not changed much. The patches on the plant in the second photo have all appeared in the last few days.

Am I right in thinking that it is mosaic virus?

Any thoughts would be greatly appreciated.

[Potstubsdustbins]

Just a few thoughts for you to think about.

Have you had an attack of greenfly for they are mostly responsible for the spread of MV.

You post that the first patch is pretty much the same as when it first appeared MV is progressive and I would have thought it would have got worse by now.

If the patches are papery I would think the most likely diagnosis would be sun scald are they under glass and are they shaded?

Potty

[SteamedSprouts]

Thanks for replying so quickly.

Have you had an attack of greenfly

No, I have not noticed any greenfly at all.

You post that the first patch is pretty much the same as when it first appeared MV is progressive and I would have thought it would have got worse by now.

I thought that might be the case, so was quite hopeful when it didn't spread. However, I do think that there are now a number of new yellow spots appearing, which I think are just about visible on the picture.

Also, the discolouration on the second plant has progressed pretty quickly.

If the patches are papery I would think the most likely diagnosis would be sun scald are they under glass and are they shaded?

They are not shaded, and get a lot of sun during the day, but they are not under glass.

The discoloured areas do not appear to be papery, they seem just like the rest of the leaves, just discoloured.

Thanks for the advice so far. It's much appreciated, because I am trying to decide whether there is risk to other vegetables, and so whether I should dig these pumpkins up.

[SteamedSprouts]

I wonder. Is it possible that it could be a magnesium deficiency?

I am loathed to pull the plants up, without being sure that it is mosaic, but I'm also worried about infecting other crops.

[rustylady]

Why are people getting so steamed up about deficiencies and viruses?

If you are growing in branded compost or normal soil then deficiencies are extremely unlikely.

It doesn't look like mosaic virus to me, but it might help a bit if you tell us where you are and what you are growing the plants in.

Also, things like mosaic virus are usually specific to a particular type of crop (e.g. cucurbits) and won't affect unrelated crops growing nearby.

[SteamedSprouts]

It doesn't look like mosaic virus to me, but it might help a bit if you tell us where you are and what you are growing the plants in.

Hi. I'm in London. I grew them from seed in a propagator, transferred to small pots and then planted in garden when they had two decent sized (10p piece) leaves.

I planted them in pockets (12 x 12 x 12 inches) filled with half soil (ph 5.5) and half branded compost (not sure which brand now).

Yesterday the leave that has the most discolouration on it had started to blister quite obviously, so I dug it out. I also took the leaf from the other plant and a leaf from a third plant that seemed to be showing the same signs.

There are now three plants left in that row, I also have two further plants that are about two weeks earlier in the growing cycle, and are about 10 feet away. They may have a couple of very small yellow spots, but nothing very definitive.

Also, things like mosaic virus are usually specific to a particular type of crop (e.g. cucurbits) and won't affect unrelated crops growing nearby.

At the moment, my other crops are peas, french beans, sweetcorn, carrots, cauliflower and kohl rabi.

I understood that quite a lot of crops can be affected by mosaic, for example I used that "pea western ringspot virus" is actually mosaic virus.

So, is the strain that affects cucurbits different from the one that affects peas?

[SteamedSprouts]

In the few days since removing that plant and taking those leaves off, the remaining plants have been growing quickly.

I have now noticed a very definite patch growing on the plant in the same row that was untouched.

Given that they were planted in half soil/half branded compost - is it worth trying to add trace nutrients, or should I try removing newly affected parts of the plants?

[rustylady]

Why don't you just leave them alone and see how they get on?

I can't understand why you planted them in "pockets" - what is wrong with your garden soil?

[WPG]

Hi SteamedSprouts. The first few leaves on my uchiki kuri squash had very similar mottling to your photos. I wasn't sure what the problem was, so gave it some epsom salts (just in case) and then a week later gave it some comfrey tea. That was a few weeks ago, and it's since flowered and is growing like a triffid, no more yellowing. Hopefully your pumpkins will recover the same.

[SteamedSprouts]

Why don't you just leave them alone and see how they get on?

I can't understand why you planted them in "pockets" - what is wrong with your garden soil?

I was concerned that, if it was mosaic, it might spread to the other pumpkin plants I have, so I felt that I should take action to protect the other plants.

I planted them in pockets as I was following the guidance in a book (The Vegetable and Herb expert)

Hi SteamedSprouts. The first few leaves on my uchiki kuri squash had very similar mottling to your photos. I wasn't sure what the problem was, so gave it some epsom salts (just in case) and then a week later gave it some comfrey tea. That was a few weeks ago, and it's since flowered and is growing like a triffid, no more yellowing. Hopefully your pumpkins will recover the same.

Thanks.

I have not given them anything except some tomato fertiliser, but they do all seem to be growing very strongly now. I removed a further leaf that seemed to have developed a patch.

I thought that there were some further spots developing on other leaves, but along with the rapid growth of the past couple of days, those spots seem to have disappeared (or at least become much less noticeable).

I'll keep my fingers crosses and, if I see further mottling, I will try epsom salts and comfrey tea as you suggest.

Thanks again.