Stress is cumulative. In other words, trees and shrubs can be affected by stresses that happened up to several years in the past.  Recent stresses in Kansas include sharp drops in temperature in the fall before some trees had hardened off.  This occurred in 2019, 2020 and 2022.  This was accompanied by last fall and winter’s extremely dry weather which often resulted in damaged root systems.  This damaged root system may have been further weakened due to too much rain in some part of the state and continued dry weather in other areas this spring.  The excess water in areas that received it harmed root systems due to saturated soils driving out oxygen.  Roots need oxygen as much as they need water.  Though the roots were able to keep up with moisture demands during the cooler spring weather, they may not be able to keep up when the weather turns hot and dry. Such trees and shrubs may suddenly collapse and die or slough off branches they can no longer support

This does not mean that all of our plants are doomed.  Some plants are just better adapted to our tough Kansas conditions and have suffered little to no harm.   However, it is a good idea to check the overall health of your trees.  So how do you tell?

One of the most important clues in determining the health of your trees is the amount of new growth that tree has produced. A healthy tree should have a minimum of 4 to 6 inches of new growth each year and usually much more. Check branches with the tips in the open and not shaded by the tree itself. Anything less than 4 inches on the majority of branches suggests the tree is under a great deal of stress.

The only thing poor growth  tells you is whether a tree is under stress or not. It does not tell you what is causing or has caused poor growth. This year, the most common cause by far is environmental stress caused by the dry fall and winter followed by excessive rain this spring.

So, what do we do for trees under stress?  The most important practice is to water as needed.

Ward Upham, Extension Agent

Two common leaf-spot diseases will likely appear on tomato plants soon if they haven’t already. Septoria leaf spot and early blight are both characterized by brown spots on the leaves.

Septoria leaf spot usually appears earlier in the season than early blight and produces small dark spots. Spots made by early blight are much larger and often have a distorted “target” pattern of concentric circles. Heavily infected leaves eventually turn yellow and drop. Older leaves are more susceptible than younger ones, so these diseases often start at the bottom of the plant and work up. Mulching, caging, or staking keeps plants off the ground, making them less vulnerable. Better air circulation allows foliage to dry quicker than in plants allowed to sprawl.

Mulching also helps prevent water from splashing and carrying disease spores to the plant. In situations where these diseases have been a problem in the past, rotation is a good strategy. It is too late for that now, but keep it in mind for next year. Actually, rotation is a good idea even if you have not had problems in the past. But many gardens are too small to make it practical. If you have room, rotate the location of the tomatoes each year to an area that has not had tomatoes or related crops (peppers, potatoes, eggplant) for several years.

 If rotation is not feasible, fungicides are often helpful. Be sure to cover both upper and lower leaf surfaces, and reapply fungicide if rainfall removes it. Plants usually become susceptible when the tomato fruit is about the size of a walnut. Chlorothalonil is a good choice for fruiting plants because it has a 0-day waiting period, meaning that fruit can be harvested once the spray is dry.

Chlorothalonil can be found in numerous products including Fertilome Broad-Spectrum Landscape and Garden Fungicide, Ortho Garden Disease Control, GardenTech Daconil, Bonide Fungonil and others. Be sure to start protecting plants before these diseases are first seen if they have been a problem in the past. It is virtually impossible to control these diseases on heavily infected plants.

If chlorothalonil doesn’t seem to be effective, try mancozeb (Bonide Mancozeb Flowable). Note that there is a five-day waiting period between application and when the fruit can be harvested.

You may wish to pick some tomatoes before they are fully red just before you spray if you use Mancozeb as the tomato fruit will ripen inside.

Ward Upham, Extension Agent