Are you familiar with the condition called 'blossom drop'? There is a FAQ here that explains the effect that humidity, dry winds, excessive nitrogen, and most important the air temperatures have on tomato plant fruit set.

The larger fruit varieties are often more affected than the small fruit varieties which is one reason why you can't really compare varieties, But all tomato plants are susceptible to blossom drop effects.

What you describe is normal for many of us in the warmer zones and for most of the country this year. Early as possible planting gets us fruit set early on, as the temperatures rise the plants essentially go dormant, and then as the weather begins to cool we get additional fruit set.

Dave

Here is a link that might be useful: Blossom Drop FAQ

Thanks Dave. I knew something about blossom drop but didn't think this was the problem since all my other tomato plants were setting fruit just fine. When I read that it is more typical with large fuited varieties then it makes sense.I guess I need to get my tomato plants in the ground earlier and keep on planting Amish Paste since they do produce some very large tomatoes but do not seem to be as affected by blossom drop as Brandywine and Pruden's Purple.

Don't mis-understand me please. Amish Paste can also experience blossom drop given the right conditions - mine shut down just like all the others do. But normally you are much cooler in your zone than I am - I envy your normal weather - so be sure to also watch out for the role excess nitrogen can play in it.

Dave

I have to admit that each plant variety is different. I have 10 different heirloom tomatoes in my garden. 3 varities get 5 hours of sun and remaining varities get full sun from sunrise to sunset. the ones that get half the sun are luch green and producing good tomatoes. The one in full sun is not so luch and yet producing good tomatoes. Brandywine continues to get BER no matter what I do and is yet to set fruit. All plants get watered equally and in a timely manner.

I have 2 Brandywine plants growing in 18 gallon containers on my balcony. They get direct sun from +/- 7:30 am till +/- 4:30 pm. This has been another extremely hot/humid summer in Baltimore, days in the 90s/100s and nights in the high 70s and low 80s since the end of June. As of today 8/9/11 one plant produced 23 and the other 24 ripe nice sized tomatoes, with many more green ones still on the vine. Neither plant had noticable blossom drop compared to my Mortgage Lifters.

Do you get your seedlings from the same source every year? Maybe you can try getting them from a different source and see if that's the cause of your low yield.

Thanks per2011. I usually start my own plants from seed. I think my main problem is that I don't start them soon enough nor get them in the ground as early as I could. According to information I got from digdirt(Dave)they are not setting fruit before the hot weather hits. The plants are healthy and beautiful, not over fertilized. I Have picked some from each plant and now they are setting fruit again since it is no loner as hot during the day and night.