Environmental

I have been seeing some ozone damage to cucurbits and oddly to tomatoes over the last 2 weeks or so, which is not unusual with the hot hazy conditions we are having. Ozone is the most common air pollutant in the eastern United States.

An odd cold/frost event occurred in a potato field just this past weekend (May 9 and 10). On Saturday morning the grower noticed dark brown necrotic areas appearing on some of their potato plants (fig. 1). Up-close some of the leaves with the necrotic areas appeared to have white fuzz on the underside of the leaf (fig. 2), which could indicate late blight.

This heat wave we have had this past week will have repercussions over the next few weeks as the flowers of several crops including cucurbits, peppers and especially tomato will not pollinate or fertilize properly to develop into fruit. Daytime highs of 90o F and above and nighttime lows only getting down to 70o F in much of the midAtlantic for the last week will cause blossom drop and fruit abortion in tomatoes.

It has been an unusually cool April, especially the last 2 weeks. This is following a warmer than average March. If you have strawberry plants starting to flower the flowers are going to be susceptible to cold damage during one of our chillier nights.

Last week Gordon Johnson had an article talking about cold damage to peas and there also has been some cold damage and weather induced damage to vegetables in high tunnels and greenhouses.

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.

Air Pollution and its Effect on Vegetables

Starting to see some watermelon, cucumber and other cucurbit crops that are looking a bit pale green or even yellow (fig. 1). Sometimes the plants have brown speckles or spots on them that may look like a foliar disease has started (fig. 2).

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.