Nevada County Picayune and Gurdon Times Newspaper Archive

Tim's Tips

Tim Clarke, County Extension Agent

- Staff Chairman

DEVELOPMENT

OF LAWN DISEASES

Here are some lawn diseases homehowners should be on the lookout for.

Dollar spot produces golf ball size dead spots on bermudagrass with straw-colored lesions across leaf bordered by reddish-brown margins.

Cool season brown patch produces circular areas of blighted turf appearing during cool, humid weather.

Pythium blight produces six-inch, roughly circular, reddish-brown spots in warm season lawn species. Unlike dollar spot, where only foliage is damaged and plants often recover quickly, Pythium-blighted plants usually die.

Spring dead spot is common on bermudagrass and appears as large, circular, straw-colored dead spots or as circular patches with doughnut shaped depressions that give the area a pock-marked look.

LEAFSPOT DISEASES

And, here are some dieseases to watch for on your ornamental shrubs.

Entomosporium leafspot of Photinia produces purple to maroon lesions on Photinia and occasionally on Bradford pear. Dispose of fallen diseased leaves in the fall.

Anthracrose of trees (including maple and oak) has been found to cause severe defoliation in certain years. Generally, a fungicide is not recommended unless trees have been defoliated at least two years in a row.

This disease can kill younger trees by lowering winter hardiness if trees are not properly managed. When this disease occurs, maintain stress free environment by ample watering and balanced fertilization.

Phyllosticta leafspot of Aucuba can be quite damaging this time of the season. It is often worsened by scale damage, therefore, control calls for combined scale insect and fungus control.

DEALING WITH

Problem soils are like bad weather, they are difficult to deal with. Soil problems can be grouped into three major categories: physical, chemical and biological.

Examples of soil physical problems include such things as compaction, plowpans, water holding capacity and wetness. Chemical problems include such things as pH, salts, infertility, toxic elements and nutrient deficiency. Biological problems include nematodes, soil borne diseases, insects and other organisms.

Common techniques used in diagnosing problem soils include visual inspection of soil or plants for symptoms, testing of soil, plant or irrigation water and analysis of plants or soil for diseases or nematodes.

Problem soils are areas in a field where plants will not grow properly. Routine soil testing is available to all Arkansas residents at no charge and is a good place to start.

Obtain a composite sample from both the bad area and a nearby area where plants are growing normally. Take the soil samples to your county Extension office and ask for a routine analysis. You can expect results back from the lab in about 10 days to three weeks depending upon the seasonal rush.

If toxic levels of heavy metals or pesticides are suspected, soil samples can be submitted to the Agricultural Service Lab at Fayetteville for analysis. Details about what can be tested for and the cost of testing is available at the Nevada County Extension office in Prescott.

If a crop is in jeopardy, plant samples may be selected for plant nutrient analysis or disease diagnosis. Samples can be submitted through county Extension offices to the appropriate service labs.

Visual symptoms may be misleading. Only under extreme conditions of deficiency, toxicity, disease or mechanical injury are they clear cut.

Sometimes visual plant symptoms are like a headache. They tell you something is wrong, but not the exact cause. The next step is to use the other tools at your disposal to determine what caused the symptoms. Start with a review of the history of the field. This includes fertilizers and pesticides applied to previous and present crops, weather conditions, soil physical properties and similar problems of the spot.

If the probable cause of the soil problem can be identified, the next step is to confirm it. This usually means some kind of remedial treatment.

If the treatment works, you have the answer. If not, go back to the drawing board. This can get to be expensive. University researchers, specialists and Extension agents can draw upon their experiences in helping landowners overcome problem situations.

CONTROLLING HORN FLIES

The horn fly season is here in Arkansas. In late March and early April the adults emerge and begin the life cycle.

Control practices should begin in May or early June when fly numbers increase enough to cause production losses.

The horn fly -- about half the size of a house fly -- has piercing, sucking mouth parts and remains on cattle day and night, leaving only to lay eggs in freshly dropped cow manure.

The adults live about three weeks and feed exclusively on cattle blood. There are several generations of flies in a grazing season. The annoyance caused by hundreds of horn flies causes the potential for weight gain and milk production to be reduced.

Cattle producers should understand the problems associated with using the same control year after year.

Different levels of fly resistance to ear tags exist throughout Arkansas. In areas where only ear tags have been used for several years, it is difficult to get acceptable control with either pyrethroid or organophosphate tags.

It is imperative to switch to a spray, back rubbers or dust bag fly control program for about two years if nobody in a given area is getting satisfactory fly control with either pyrethroid or organophosphate tags.

If pyrethroid tags have been used for two consecutive years and you are getting fewer than eight to 10 weeks of satisfactory control (more than 200 flies per animal during that time period), it is time to switch to OP tags, alternate to pyrethroid tags or sprays, dust or back rubbers for a year or two.