[MikeyandAnnie]

Does anyone know what causes Tomato Blossom Drop?

I also think my toms are suffering some kind of virus in addition to this because some have very dark brown streaks on some of the stems, the leaves have curled up and the fruit have mottled skins on those plants.

[Ice]

Could  you post a picture?

[pushrod]

Water shortage, failure to pollinate and i believe an excessively hot or dry atmosphere can.  Also of course if the plants are indeed diseased. Are they outside or in a greenhouse?

[MikeyandAnnie]

Thanks pushrod, for your reply.

I have plants inside and outside.  The signs of virus seemed to come along some weeks after blossom drop became apparent.

The greenhouse is one with polycarbonate panes, which diffuse the light somewhat.  Would you recommend any particular type of materila to use as a shade to help control the temperature.

I do have an automatic vent opener and leave the other widow and the door open on hot days, of which there were plenty in June.

Sorry, can't post a picture, camera/phone rubbish.

[pushrod]

The easiest way might be to splatter/paint some greenhouse white wash onto the polycarbonate. Also spraying water on the ground inbetween your plants on the hottest days helps keep it cooler and more humid. Alternatively you can buy greenhouse shading (green mesh) or you can put up some pieces of white fleece. When you get your next greenhouse get bottom openings vents as well 

[MikeyandAnnie]

Thanks pushrod, I'll try the whitewash next year for sure.

 

[DavidT]

Unfortunately your tomatoes are suffering from blight. It is prevelant at the moment. I had to bin a clients 3 plants today which were yielding about 10lb of toms.

[pushrod]

Apologies - did not read your first post properly. DavidT above is correct you almost certainly do have blight the clue being the mottling on the fruit (which i didn't read ).
Plants in greenhouses are usually ok. Does it look like this

[MikeyandAnnie]

Thanks for the pic.  The fruits do look like that, only I've binned em before they got that bad.  I found that the spuds had blight, and the toms were downwind.  What more can I say.

I found it easier to identify thisease by the greasy dark brown areas on the stems - both on the spuds and the toms.

I think I might just have early spuds next year, not maincrop.  Does that sound a good precaution, given that I put my toms outdoor latish, when the weather picks up?

[pushrod]

Yes early spuds much less likely to be affected by blight than maincrop. I must admit to having given up trying to grow tomatoes outside and just keep them in a greenhouse, where (touch wood) i have never had any problems.

Spraying with Dithane is supposed to give some protection