Is Your Lawn Getting a Little Rusty?

I know there has been a lot of excitement over the Giants winning the World Series, but the fact that some lawns are turning orange really has nothing to do with baseball.  The grass may exhibit some yellow spotting initially, but as the rust advances one will see a reddish-orange powder develop on the leaf surface.  These are the spores of a lawn infecting fungus (Puccinia sp.).  Mowers, shoes and clothing can become a magnet for picking up the rust colored spores as they pass across the infected lawn transferring the spores to other lawns that may be susceptible, especially if there is a bluegrass component to the lawn mix.  If you pass your fingers across the leaf blade you will likely have the orange spores deposited on your skin.  It will not hurt you…really.

The rust colored lawns tells me a few things.  First, there is likely some Kentucky bluegrass in the lawn as that is the most likely grass type to get rust.  Ryegrass and tall fescue may exhibit some rust in rare cases here in Central California.  Secondly, rust indicates that the weather has changed and we are in a period where the days are warm (70 to 75 F) and nights are getting cooler and damper.  Spore germination and infection of the rust fungus into host plants can occur with extended periods of leaf moisture lasting 10-12 hours from dew and/or irrigation.  Other conditions like lack of water, low levels of nitrogen, infrequent mowing, and mowing too short can certainly enhance the presence as well.  Rust was noted on lawns November through June this last year, but the peak occurrence was mid March and the month of April. 

Although it can be very visible and a bit unsightly, the disease rarely causes any notable damage to the lawn.  Application of a fungicide is not usually recommended when proper cultural practices are employed.  I would be sure that the lawn has been adequately fed with a fertilizer that will promote new growth thus allowing the infected leaves to be cut and removed.  Secondly, I would make sure the lawn has sufficient water available to favor good growth and water in the early morning so that the period of wetness does not get extended further into the day.  Finally, I would make sure that the lawn is mowed weekly at 2.5 inches or higher.

Problems with Poa

Poa annua

Perhaps you have seen this invasive “winter grass” invade your lawn and flower beds at home in past years. It is a clumpy, spring-green tuft of grass that first appears in October, continues to grow denser and put out an abundance of seed mid to late winter, and finally disappears as the weather warms up in May and June.  Annual bluegrass, Poa annua, is native to Europe, but now found world-wide.  It can grow 6-8 inches tall and can tolerate mowing heights below 1/8 inch as seen on golf course putting greens.  It has been estimated that Poa can produce as many as 14,000 to 63,000 viable seeds per square foot in a year on a golf course green!  Seeds can remain dormant for a few years, but with regular irrigation, most do not show much of a dormancy period.

So, why is Poa a problem, it is green after all. The biggest problem with Poa annua in the Central Valley is that it is a true annual that will abandon you by early summer in full sun areas because it cannot tolerate the heat.  Germination will start as early as August when soil temperatures start to drop below 70 degrees.  Germination will continue throughout the winter and by December (or before) you will start to see the appearance of the open-panicle seedheads popping up.  By February and March you will see the yellow-green patches with seedheads across the lawn areas and throughout the flower beds.  Two to three months later most of the plants will only be brown tufts scattered about.  Just think about the poor golf course superintendent that has to manage greens that are mowed daily at extremely short heights, excessive summer heat, and golfers trampling over the turf throughout the day.  His job is to keep alive what Poa he has and try to minimize its further spread.

Poa annua flowerhead

So what can be done?  If possible, one should try to limit the spread of Poa by not moving the seeds with mowers from bad turf to good turf.  Mowing when the grass is dry can help somewhat, but certainly washing off the mower between lawns is obvious during periods of seeding.  Secondly, a pre emergent herbicide should be applied mid to late August to reduce the likelihood of seed germination.  One must also consider if the lawn is going to be overseeded or spot-seeded late September or early October.  The pre emergent will possibly cause a poor or weak stand of new seedlings as the herbicide will reduce root development.  There are a few options for selectively controlling Poa annua in existing lawns, but they are not available to homeowners and generally they are specific for either warm or cool season grasses. 

Controlling Poa annua in lawns can be tricky, but it’s a no-brainer to apply a pre emergent now in flower beds to interrupt the life cycle this winter and save you a lot of work pulling weeds this spring.

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Why is My Lawn Brown?

This is not an easy question to answer without first asking a few background questions. If the spots are irregular in shape, and not round, I would start with the sprinkler system.  Do you have automatic sprinklers, manually operated sprinklers, or none of the above?  How often do you water? When do you water?  How long do you water?  Next I would look at the sprinklers while they are running.  Are they operating properly?  Is the spacing allowing head to head coverage?  Are there any shrubs or trees blocking the pattern?  Are the heads level and adjusted to the right height? 

Dry spot from lack of water

A soil probe can take a core sample of the top 4-6 inches and tell you if the soil has adequate water and how deep down the water has traveled.  Ideally, you would see good moisture down 4-6 inches deep.  If you can’t get the probe down below 2-4 inches, the soil is likely water deficient.  A standard 6-8 inch screwdriver can also be an easy tool to probe how far down the soil is moist.  Generally, you should be able to push the screwdriver down 4-6 inches with moderate effort.  Too easy…too wet; too hard…too dry.

Pythium Disease

Brown lawns could also be the result of numerous pests.  Diseases generally cause circular yellow-brown patterns in the lawn and symptoms vary with the pathogen involved.  Insect damage can be somewhat random in appearance.  Some pest attack the roots causing failure of the lawn in patches while others feed on the leaves causing thinning or yellowing.

Lastly, and you may not want to hear this, but there could be several cultural habits that cause a lawn to fail during stress periods.  Over watering or watering frequently, especially in the evenings, could encourage disease activity.  Over fertilizing, especially spilling fertilizer, can cause rapid browning due to the high salt content (like pet urine burns).  Mowing too short, too infrequently, or with dull mower blades can stress the lawn as well.  Ideally they should be mowed at least weekly and at the proper height for that particular grass type.  There are also the odd things like sunlight reflection off a large picture window, placing car floor mats on the lawn while cleaning the car, construction cleanups, and space aliens landing at night. 

Hopefully, you now have some ideas on how to troubleshoot your brown spots, or you can always give us a call for a free analysis.  The weather is going to become cooler shortly and many of this summer’s brown spots will be disappearing for several months. Hooray!

Winter Weeds Have Arrived!

I am into weeds. I will apologize upfront.  We are still facing very warm and sometimes hot days, but I have noticed the appearance of several winter annual weeds starting to emerge in lawns and flower beds.  I have seen a lot of sowthistle, prickly lettuce, and Poa annua popping up the past few weeks which are indicators that our days are getting shorter and nights are getting cooler.  That’s just fine for me as I am more than ready for a cool down.

Cudweed

If you are like me, you will not want these weeds getting a foot hold in your landscape.  What can you do?  First off, I would be sure to remove or spray emergent weeds and not let them flower which will result in the further spread of the unwanted pests.  If they already are seeding, please carefully pull or dig these out and dispose of them in your green waste can.

The next step would include applying a pre emergent herbicide to both the lawn and flower beds while they are nearly weed-free and allowing the irrigation water to activate them into the top inch or so of soil.  Most of the common pre emergent herbicides (Amaze, Preen, Surflan, Halts, Dimension, and Barricade) are root inhibitors thereby stopping the weeds from developing a healthy root system while allowing existing plants to continue growing with minimal root suppression.  The above list controls a large list of grassy and broadleaf weeds, but often week on the thistle and composite families.  Commercial products often combine other pre emergent products to improve the weed control spectrum and pick up some of the more difficult weeds missed.  This includes some rather pricey products like Gallery, Snapshot, and Freehand.  Ideally, pre emergent products need to go down mid-September into October to prevent the weeds from successfully emerging this winter. Complete weed control is rarely achieved.

Another approach includes the addition of mulch.  Mulch can potentially add aesthetic value, reduce water loss, and reduce weed pressure.  Pulling weeds is often much easier with a good mulch layer.  Generally, mulch layers less than 2 inches deep are not very effective for weed control reduction. In order to maintain a 2-4 inch mulch layer, one needs to repeatedly add more mulch every few years as it breaks down over time.

Before you know it, we will be talking about crabgrass prevention and other foes like spurge, nutsedge, and green kyllinga.  Meanwhile, now is the time to plan for the coming onslaught of winter weeds in your landscape.  Good luck!

30 Days to a Better Lawn in 2013

Step outside and take a good look at your lawn.  Do you see bare spots or patches of undesirable looking grasses and weeds?  Maybe your kids’ activities, your dog’s constant pacing in the same path day after day, or your parking the car on the front lawn has caused the lawn to thin out due to wear and compaction.  Its true that the 19 straight days of temperatures exceeding 100 degrees certainly did not help our cool-season lawns either.  The lawns are beat and just looking for some tender care.

Cooler temperatures are just around the corner.  What is left of the lawn will perk up and appreciate the cool nights and shorter, milder days.  Crabgrass will stop germinating by mid to late September.  Thirty days from now life will be great!

What needs to be done in the next 30 days to have a better lawn for next year?  Get ready because this is where you come in.  Check for unwanted grasses.  Patches of Bermuda or dallisgrass are hard to kill and should be sprayed 2-3 times in the starting early September.  Dense sections of crabgrass or bentgrass are fairly easy to kill and could wait until the middle of September to spray.  If you think the lawn looks bad now just wait to see what it looks like in a few weeks!

Here’s the good news. Oct 1-10 is a great time to reseed all those problem areas.  I would strongly recommend scalping down the areas to be reseeded prior to seeding followed by a fall lawn aeration to loosen the soil and encourage better root development.  Areas could then be raked or dethatched mechanically to make a proper seed bed.  Select a quality grass to match your existing lawn and follow suggested seeding directions.  Generally tall fescue and ryegrass go done around 7-10 lbs/1000 sq ft.  Next apply a ¼ inch of clean humus or compost to cover the seed to keep in the warmth and moisture to insure good germination.  Apply a starter fertilizer like 10-20-10 at 10 lbs/1000.  Water 2-3 times a day lightly to keep the mulch and seed moist for the first 7-14 days.

Here is what NOT to do. 1) Nothing.  Your lawn will be no better next year and likely worse. 2). Sprinkle some seed over the bare spots and hope for the best.  This is not much better than option 1. 3). Buy the cheapest seed you can find like annual ryegrass.  This will result in the ugliest lawn on your block.  It never really greens up, it grows very fast and often clumpy, it does not match any grasses in your lawn, and often gets riddled with disease in the winter months.

The window of opportunity is here.  Now get outside and take the actions for a better lawn in 2013!

Are You Seeing Circles?

If you are like me, you may have spent countless hours watching the Olympic coverage the past few weeks, but I am not talking about those circles.  Lawns in the Central Valley have been taking a beating with the 15 plus days of temperatures exceeding 100 degrees. We have seen spots and circles as a result of the weather conditions favoring various disease and insect activity.

Before one jumps to the conclusion that they must have either a disease or insect problem because they see parts of their lawn turning brown, one must first see if the lawn has sufficient water in the top 4-6 inches to meet the lawn’s water needs.  If a screwdriver can be pushed into the ground 4-6 inches with moderate effort most likely there is sufficient water in the root zone.  Dry soils will only allow the screwdriver to go in 2 inches or less in non-sandy soils.

Next, one looks for patterns to the brown areas.  Are they circular spots or rings or angular?  Do the leaves have spots or lesions or are they chewed off shorter than the mower could possibly cut (possible cutworms or webworms)?

Lawn diseases are typically circular in their pattern.  Three distinct fungal pests thrive in the summer heat on tall fescue, rye, and bluegrass lawns.  Pythium is a water mold that can quickly cause small to large brown blotches in the lawn and is associated here with excessive watering in most cases.  It is not the number one problem, but it is relatively easy to reduce its damage by reducing the amount of water applied and not mowing the lawn when it is wet and or boggy.  Rhizoctonia brown patch will form small to large patches of browning turf due to the numerous tan lesions that damage the blades.  It thrives in sunny locations with poor air movement and often increases with evening watering.  Faint to distinct yellow-brown circles with green centers in the lawn ranging from 1 to 12 feet in diameter usually signals southern blight.  One can usually note little seed-like sclerotia along the outside edge in the thatch to confirm the identification. By mid September these will likely all be subsiding as the evenings start to cool off.

Cultural practices like watering deeply 3-4 times a week and avoiding irrigation in the evening may reduce disease incidence.  Preventive fungicides are available that provide up to 30 days control and are a great option for the months of June, July, and August.  Like people, the cool-season grasses enjoy the 65-80 degree weather and cool nights, but unfortunately we have no control on that.  

Relief is coming soon!

A Few Thoughts on Water Conservation

I do not claim to be fount of all knowledge on irrigation, but I can recommend a few things one can do to be more efficient in the use of their irrigation water in the landscape.  I love lawns and so I am not inclined to always jump at the idea of removing turf from the family landscape.  Actually, I would be looking for ways to keep my lawn and landscape healthy with the proper amount of water at the proper interval to encourage deep irrigation and deep healthy roots.

Three areas come to mind and one of them is planting the correct plant material for the right soil, exposure, climate, etc.  Beyond that, I think one would be very wise to look into “smart clocks” (irrigation controllers) and more precision delivery from the newer emitters.  You can make your controllers “smarter” with these new clocks that take into account the soil texture, zip code, daily temperature, rainfall, slope, plant material and so on.  The addition of a local mini weather station, or internet-based weather input, will allow the amount of time needed to run each valve to be adjusted up or down during each cycle.  This will go a long way to increase efficiency over the common method of turning the clock on in March and turning it off in late October with no regard as to the actual needs of the plants.

Finally, there is the choice of irrigation emitters themselves.  There are nozzles like the “MP Rotators” and “PrecisionSeries Nozzles” that are much more efficient in both their uniformity of coverage and the rate of delivery.  With a larger droplet size and slower rate of delivery one can greatly increase the uniformity and significantly reduce the chance of runoff.  

Check with your local irrigation supply house and see what advances have been made in the past few years.  They will pay for themselves in your water bill, your plant’s health, and conserve water.  It’s the smart thing to do.