Brown spots in lawns may be summer patch disease

      The following are typical questions our Master Gardeners answer daily at the Nevada Cooperative Extension. If you have gardening questions, call the Master Gardeners' hot line at 257-5555 between 9 a.m. and 4 p.m. Monday through Friday. There is also a gardening Web site at http://www. intermind.net/mgarden/.
     
      We have been getting many calls concerning the development of brown patches in lawns. A few months ago we did have a disease called summer patch that devastated many lawns in the area.
      The disease was diagnosed and confirmed several times by pathologists. The disease was brought about by the weather conditions and the irrigation management of the lawn.
      Water stress can predispose a lawn to summer patch. Some of the lawn problems that we are seeing now are not summer patch. They are, instead, due to management problems such as poor aeration, mowing too close and not often enough. Watering should be deep and spaced far enough apart so that the lawn has a chance to dry out between irrigations.
      Mowing should never remove more than 1/4 to 1/3 of the leaf blade. If more than this, nitrogen applications should be decreased or mowing frequency should be increased or both. Aerate lawns any time during the year particularly if you are watering frequently.
      Question: There are dead spots in my lawn from either disease or insects that are quite large. How do I fix these?
      Answer: If this is a tall fescue lawn then you must wait until it gets cooler, probably around the end of September.
      If this is a bermuda lawn then you must repair it immediately or it won't recover by fall. In late September, the fescue lawn should be mowed close but not closer than one and one-half inch.
      Check the irrigation system and make sure that you have even coverage.
      The areas which are dead should be raked until you can see bare ground. If these are large areas, you might consider renting a dethatcher or power rake to remove the dead grass.
      The seed can be sown directly into the dead areas. The lawn does not need to be cultivated. Select a superior tall fescue for home lawns, not Kentucky 31.
      These are usually quite a bit more expensive than K 31. Actually K 31 has many good qualities but most people are not happy with its coarse appearance. Fertilize the dead raked areas with a lawn starter fertilizer high in phosphorus, the middle number on the bag.
      Probably the least expensive fertilizer available to do this is 16-20-0. Spread the seed and fertilizer evenly in the raked areas. Cover with a topdressing, making sure that it is no deeper than one quarter inch.
      This can be manure if you don't mind the inconvenience of the smell and messiness. Otherwise any kind of soil that is fine-textured like a potting soil will work.
      Water the area three times a day for five minutes until the seed germinates, usually in four to five days.
      Q: My roses look terrible now. What can I do?
      A: In this climate, this is a fact of life for roses at this time of year. Heat is the major reason for their poor condition.
      I do believe that high nighttime temperatures contribute as much or more to rose problems as the high daytime temperatures and direct light.
      Roses need protection from late afternoon sun, amended soil in the root at the time of planting, good drainage, mulched around the roots, a good fertilizer program, proper pruning and attention to its pest problems.
      The No. 1 problem we see with roses is lack of attention by its owners. The next two tie for second and they are planting in the wrong location and bad irrigation practices.
      Roses need six hours of morning or early afternoon sun each day and protection from late afternoon heat and sun. They need a well-prepared soil at the time of planting and an organic mulch that will decompose and add organic matter to the soil, not a rock mulch. They need drainage from irrigation water.
      As soon as the evening temperatures get comfortable begin a light fertilizer program with them to bring them back to health. Use a fertilizer made for roses if you don't have a favorite that you've discovered.
      These plants require attention and cannot be treated like a landscape shrub. If you do treat them this way, you won't be happy with them.
      Q: My agave fell over. It just died overnight. What happened?
      A: This is probably the agave weevil. If you were to dig up the plant as soon as it died you would see the root filled with holes and small insect larvae inside the root.
      The insect larvae feed on the inside of the plant and root system and kill it when there are enough numbers to cause extensive damage. Usually a drenching of the soil surrounding the root with an insecticide, or spreading insecticide granules, will kill the insects and save the plant.
      Try drenching the root area with neem which is safe for all mammals. Watch for adults crawling around the plant.
      These are quarter inch, dark-colored weevils. This is a good indicator for the presence of the weevil.
      Q: I have a problem with my okra. The plants were normal and full of blooms, but did not set fruit. Eventually the blooms dropped off. What's the deal?
      A: Your okra could have shed its flowers for a number of reasons but most likely irregular watering. Though okra revels in summer heat, dry periods affect fruit set and development. Keep your plants well-watered and maintain a two- to three-inch layer of compost mulch around the plants.
      When planted from seed, okra needs about 60 days of midsummer weather to produce a crop. Okra cultivars differ in height, pod color, prominence of pod ridges and presence of spines. Okra will produce large flowers about 2 months after planting.
      The okra pods will be ready to pick 3 to 4 days later.
      Harvest the pods when they are 3 to 4 inches long. The seedpods should be refrigerated immediately following harvest. If the okra gets too large, it will be tough and stringy. Pick the okra every 1 to 2 days or yields will be decreased.
      Okra which is too mature can be dried, cured and used in flower arrangements. Okra is very sensitive to frost.
     
     Bob Morris is a horticulture specialist with Nevada Cooperative Extension.