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Monday, February 13, 2012

Pyracantha Has No Berries

Q. Would you happen to know why my eight pyracantha bushes did not produce red berries this year?  I did not see birds helping themselves.

A. On your pyracantha the only thing I can come up with is either that they did not flower (you did not tell me if they flowered or not) or that a late freeze eliminated the fruit crop. We did have a late freeze in the spring which eliminated many plums and apricots this past growing season.         

Another possibility could be how they were pruned. If they were pruned in such a way that the flowering wood was removed, then it is possible the fruit would be removed as well. If your pyracantha bloomed this past year and did not fruit then this means it was most likely a late frost. I hope this helps.

Small Dark Green Circles on Lawn

Q. I have nice green circles on my lawn. Yes, I have three dogs!  The lawn was put in about nine months ago as sod.  It suffered from minor fungus last summer and those areas were resodded about three months ago which you can see in my photo.  About a week ago I added a nitrogen only fertilizer.  Do I need to add something else to the lawn?  I would like the lawn to look green like the circles which I assume are a result of my dogs!  Or is this some other issue?

A. Thanks for telling me you have the dogs. You must read my column. Green spots or small circles can be from dogs. If it is from dogs, the spots are usually 6 to 10 inches in diameter with a smaller circle of dead grass in the center.
Dog urine damage to lawn. If the lawn had been fertilized
with a high nitrogen fertilizer at Thanksgiving the circles
would not be as notieable
            The concentrated dog urine kills the grass in the center of the green spot due to its concentration but acts like a high nitrogen fertilizer as it becomes more dilute further from the dead grass. The diluted dog urine causes the grass to become greener and grow more rapidly. So the dark green grass surrounding the brown dead center is frequently taller than the surrounding grass.

            If it is warm outside, an application of high nitrogen fertilizer plus one or two mowings to remove the brown dead tips of grass should even the color out through your lawn. Nitrogen is the primary fertilizer responsible for having a green lawn. The other is iron. You cannot substitute one for the other. Nitrogen also stimulates growth. Adding more nitrogen means mowing more often.

            Your lawn is very dense in the picture. This might also contribute to disease problems. You might try reducing your fertilizer applications to about half of what you are applying now to decrease its density and help improve air movement through the grass. This might help reducing disease potential when it is hot outside.

            You could also try mowing your lawn a bit shorter in the summer months, no shorter than 1 1/2 inches. This might also help reduce disease potential. Make sure you are irrigating your lawn in the early morning hours, not at night where the water can sit on the lawn for several hours before it evaporates.

            I have a class coming up on lawn care management on Sunday, February 26 at noon at Plant World Nursery.

Controlling Bermudagrass in a Fescue Lawn

Q. I spoke to you about my patch of Bermudagrass at one of your classes. You said that Bermudagrass could be controlled just by letting a fescue lawn shade the soil. Can I really get my Bermudagrass under control simply by mowing higher?

Winter fescue lawn with dormant bermudagrass now obvious.
Invasion of bermudagrass is because sprinklers cannot irrigate
a triangular patch of grass efficiently. Under irrigation =
bermudagrass in the hot desert.
A. No, you cannot control existing Bermudagrass in a lawn just by letting the fescue grow taller. I think I was misunderstood. Once you have a fescue lawn established, by keeping the soil shaded you will reduce and possibly eliminate Bermudagrass from getting started. This is what I intended to be heard.

            Bermudagrass cannot survive in shade. By keeping the soil surface shaded by a healthy lawn, Bermudagrass will be discouraged. Bermudagrass invades a home lawn where lawns are mowed too short or damaged, thus eliminating shade on the soil surface. Typical places where it invades include around sprinkler heads and the edges of the lawn near concrete. Both of these places are where line trimmers are frequently used to keep grass shorter.

            It also invades damaged areas due to under irrigation, disease or insects. Once established in the lawn, Bermudagrass is nearly impossible to eliminate without renovating the entire lawn. This would mean fertilizing, watering and mowing the lawn to get it as healthy as possible and then killing it with Roundup.

            This is best done in the fall around mid-September to mid-October. About 10 days after the Roundup application or applications, the lawn can be mowed extremely short, power raked until you see bare soil and reseeded directly into the dying or dead lawn.

            The key to eliminating the Bermudagrass will be getting a thorough kill with the Roundup before replanting. Spray once, mow in two days and spray again going 90 degrees to the first spray to get good coverage and a better kill.

Ferilizing Photinia, Iris, Hollies and Italian Cypress

Q. I want to know when and how to fertilize most of my shrubs.  I have a lot of Photinia, iris, Japanese hollies and Italian cypresses.
Iron chlorosis on photinia in rock mulch

A. Flowering plants should be fertilized a few weeks just prior to flowering and the development of new growth. If flowering and new growth coincide with each other, then one application of fertilizer just prior to that combined event is all that is necessary.
            If new growth starts and then flowering occurs later, then you should probably fertilize a second or even third time during, or slightly after, flowering. Usually if we grow plants specifically for their flowers (roses are a good example) then regular applications of fertilizer through their flowering season might be considered. A slow release fertilizer could be substituted for multiple fertilizer applications.
            Once they stop growing in late summer and fall, they send food reserves into storage. So they should have nutrients available to them during fall as well. We sometimes call this late fall fertilization. This can be advantageous for woody trees, shrubs and even lawns.
            Generally speaking we can fertilize most plants once in the spring, now, and be done with it for the remainder of the year. Flowering plants that we appreciate for their flowers need to be fertilized a bit more often; once prior to new growth and then again after blooming to help build up reserves. So your iris probably fit into the second category. The others, into the first category.

Apply the fertilizer close to the source of water that is irrigating the plants and let the irrigations take the fertilizer into the root zone.

Crocus and Tulips Coming Up Early and Protection from Freeze

Q. My crocuses and tulips are poking their heads out of the dirt in my garden. They’re growing. We have had great "spring weather" in January. Should I let them continue or should I put some more dirt on them?

A. Don't do anything to them. They should be fine unless we get some unusually cold weather for this time of year. If you get nervous because of some predicted cold temperatures, just lay a sheet or light blanket over them until it warms the next morning.

            Next winter in December you might cover them with a layer of loose mulch such as wood chips a couple of inches thick to help keep the soil cool and reduce their response to warm weather. This will help slow them down in cases such as these where we have warm January weather.