Tomatoes

Last week Gordon Johnson had an article about exhaust problems for greenhouse transplants. In Maryland we have seen a few problems with ethylene interactions with tomatoes in high tunnels. Ethylene (C2H4) occurs in trace amounts in gasoline and natural gas and is produced when these substances are burned. It also is present in wood and tobacco smoke.

Tomatoes are grafted by joining the top part of one plant (the scion) to the root system of another plant (the rootstock) (fig. 1). The resulting plant is usually more vigorous and productive.

There have been some reports from growers and educators of several sets of tomato fruit with catfacing or that are deformed (Fig. 1). Catfacing results in fruit with deep indentations in the blossom end or fruit with significant distortions. It is thought to be caused by a problem during the formation of the flower that results in the fruit not developing normally. However, there is little information as to its exact cause. At times the first set of tomatoes in fields looked good, but the second, third and in some cases 4th sets are having problems in some fields. The problem is most probably due to the cool night temperatures we had 20-30 days ago in some areas.

This is just a reminder with the peculiar weather we have had lately with stretches of very high temperatures then cooler days and throw in the very heavy down pours we have had over the last few weeks, blossom end rot can become a real problem in tomatoes.

Another disease we might be seeing now and in the next week or so is late blight. The weather conditions of the past week have been favorable for its development: cool (for summer temperatures) daytime and nighttime temperatures along with ample moisture.

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.

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.

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.

Tomato Pollination and How to Increase it in High Tunnels

The Brown marmorated stink bug (BMSB) Halyomorpha halys (Figs. 1 and 1a) was accidentally introduced into the United States in shipping containers arriving from Asia. The first confirmed specimen was collected in Allentown, PA in October 2001, although there is evidence that it was collected from black light traps in New Jersey as early as 2000.