Tomatoes

Over the last month I have received reports from high tunnel (HT) growers that were seeing flower abscission due to poor pollination in their tomatoes (fig. 1). Some of these reports were a few weeks ago and others were just this past week. There are unfortunately several factors that can cause poor pollination in tomatoes.

The high temperatures we have had this week and probably next week with daytime highs at 90oF and above and nighttime lows only getting down to 70oF in much of the mid-Atlantic may cause blossom drop and fruit abortion in tomatoes. Ordinarily in tomato fields pollination is achieved just by the action of the wind. Pollen is released from the tomato flower and falls onto the stigma.

I have seen several sweet corn fields lately that have sulfur deficiencies (fig 1). One of the possible reasons we are seeing more S deficiency is because less sulfur is being deposited into the soil from the atmosphere due to reductions in acid rain. In 1986 about 24 lbs/a of sulfate were deposited in Maryland soils per year, however in 2011 it was closer to just 8 lbs/a each year. Organic matter supplies most of the sulfur to the crop, but sulfur must be mineralized to sulfate-S to be taken up by crop plants.

Nutrient Problems and Their Management in Tomatoes

Over the last few months in our area there have appeared problems with tomato ripening. The ripening problems are called various names such as blotchy ripening, yellow shoulder, grey wall, internal whitening, etc. (fig 1).

Normally at this time of year, I’d be writing about how bad yellow shoulders and other fruit ripening problems are in Maryland tomatoes. But this has been a strange season with May weather in March and March weather in May, which caused a great deal of catfacing problems this year. However, except for a few fields in a few places there have been far fewer troubles with tomato yellow shoulders or fruit ripening problems than we normally see this time of year—at least for now. Why is this?

A root disease that is most commonly associated with potato has turned up on tomato in a high tunnel last week. This disease goes by the delightful name of black dot root rot. The causal agent is Colletotrichum coccodes, which also causes anthracnose fruit rot on tomato (sunken, water-soaked, circular lesions).

Southern bacterial wilt of tomato, which is caused by the soil-borne bacterium Ralstonia solanacearum Race 1, has been found in a couple of tomato fields in the past week. This pathogen affects many solanaceous crops and is found throughout the southern United States.

Bacterial Canker of Tomato

Southern bacterial wilt of tomato, which is caused by the soil-borne bacterium Ralstonia solanacearum Race 1, has been found in several tomato fields just recently. This pathogen affects many solanaceous crops and is found throughout the southern United States.