July 14, 1993
Leaf Spot - turf
The period from mid-July to mid-August is the time when Iowan's will notice our most consistent perennial accidental invaders, the strawberry root weevil and the imported longhorned weevil. Both are harmless but annoying pests that wander in from outdoors, often in fairly large numbers.
Another two weeks of rain, tornados, and wind have caused trouble throughout Iowa since the last newsletter. Where will it end?? Trees suffering severe injury as a result of these storms aren't always the luck of the draw. Certain tree species are much more susceptible to damage than others. For instance, silver maples, Siberian elms, willows, green ash, and hackberry can suffer considerable damage. Sugar maples, Norway maples, basswoods, and oaks sustain only light damage. Other factors that play a part in storm damage include age and maintenance history of the tree.
With the extensive flooding occurring throughout the state, numerous calls have come to "Hortline" regarding the edibility of flood-damaged fruits and vegetables. The most important thing to determine is whether the garden area was flooded by sewer backup or rain water. Plants and produce should be discarded if sewage was involved. If the damage is from flood water or standing rainwater, the produce is safe to consume if it's firm, unblemished, and the plant remains healthy and survives. Watching the garden area for the next one to two weeks will help you make the decision.
The excessive rains this spring and summer have caused extensive flooding across many areas in Iowa. Turfgrass areas in home lawns, parks, recreational areas, and golf courses have been damaged by flood waters. Turfgrass damage has been due to erosion, deposition of soil and debris, or simply submersion under water.
Rapidly moving flood waters can cause extensive turf and soil erosion. Damaged areas will need to be repaired and seeded or sodded this fall.
How long can trees survive flooding before injury results? As you might expect, this has become an all too frequent question lately as torrential rains and bloated rivers continue to plague many regions in Iowa. Fortunately for most trees, the prospect for survival and continued growth is good. Even flood-sensitive trees will escape injury if flood waters recede in seven days or less. But, if flood waters cover roots of sensitive trees for longer periods, injury symptoms such as leaf chlorosis (yellowing), downward curling of leaves, leaf drop, and branch dieback may occur.
Our on-farm IPM trials have ended for June-bearing strawberries, but are continuing for apples. Some preliminary findings: