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. We are seeing many samples come in of trees suffering the effects of the high heat we’ve been having. Many trees are struggling now with scorched leaves, which shows as evenly discolored spots on leaves, typically from the tips inward but not always. The discolored area have no rings, halos or fruiting bodies - if you see any of those things, you should suspect fungus or bacteria. Often we see leaves that are dry, slightly curled, but NOT discolored from heat injury. On pines, the needles will be browning with no rings or banding, and will be brittle and dry. There is little the homeowner can do for this.
. This is a good opportunity to review what iron chlorosis is and it’s effects on plants.
From fact sheet 7.728: "Iron chlorosis refers to a yellowing caused by iron deficiency in the leaf tissues. The primary symptoms include interveinal chlorosis, i.e., a general yellowing of leaves with veins remaining green. In severe cases, leaves may become pale yellow or whitish but veins retain a greenish cast. Angular shaped brown spots may develop between veins and leaf margins, along edges, may scorch.
Iron is necessary for the formation of chlorophyll, which produces the green color in plants and is necessary for photosynthesis. A reduction in chlorophyll during the growing season reduces plant growth, vigor, and tolerance to stressful conditions. Plants with reduced vigor from iron chlorosis are prone to winter injury as well as other diseases and insect infestations."
finishes our list of commonly asked problems. Tomatoes are showing symptoms of blossom end rot, curly top virus, and 2,4-D damage. If the tomato isn't dead from the herbicide, it will grow out of the damage.
If the bottom of the developing fruit has a brown soft, rotten appearance, this is blossom end rot. Irregular watering is to blame for this condition here in Colorado. In other areas, a lack of calcium is also a culprit, but we typically don't have a calcium deficiency in our soils.
***side note: tomatoes don't set a lot of fruit during high heat, so if you are worried about slow fruit development or a lack of fruit set, be patient and the tomatoes will really take off in August – September.
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