This statement has really amazed me, “I didn’t think my tree would die and since my tree died it must have a contagious disease or insect problem.” Well I guess most folks don’t consider it strange but considering the severe drought it sure seems like lack of water would be blamed first!
First trees do get old and die. We do hear about trees that are hundreds of years old or even some trees recorded to be thousands of years old but generally speaking trees live less than 50 years with some maybe living to be a hundred years old. In this part of Central Texas we do have a few trees that are really old but most have only been around 50 years or less. Williamson County is essentially two very different ecological areas with the west half being Hill Country and the east being Blackland Prairie. Neither region is noted for having old, old trees mostly because of the shallow soils.
Trees die for a variety of reasons but insects and disease are not normally the primary. We do have a problem with Oak Wilt in some species of oaks but outside that we lose trees mostly because of physiological problems typically caused by the environment. One of the primary reasons is shallow soils. As trees get bigger they need more room both in the top and also in the roots. Shallow soils inhibit root growth and if we cant grow roots we cant grow top. We could also add overcrowding to this problem, too many trees in too small a space. Then along comes a once in a lifetime drought and trees simply fall apart. They were cramped and crowded to begin with and now there is a lack of water to both cool the tree, move nutrients and supply plant cells. It is no wonder they die!
Once stressed trees are then more susceptible to all kinds of insect and disease problems. One of the primary causes of oak tree deaths right now is Hypoxylon Canker which can only affect an oak when it is stressed. But I am also seeing hackberry, elm, pecan, magnolia, and cedar die every day simply because it is too dry.
Now back to the Oak Wilt disease which is a severe problem in all of Williamson County and certainly all of the Hill Country. The Texas AgriLife Extension Service and the Texas Forest Service have conducted numerous programs about Oak Wilt and its treatment for area residents. Recently though we offered an intense one day shortcourse on Oak Wilt for our Master Gardeners to certify them as Master Gardener Oak Wilt specialists. Over the last two months we have been directing call to the Extension office about Oak Wilt to these specialists and the public has had nothing but praise for this team. If you think you have Oak Wilt or just want to know more about it call or send an email to the Williamson County Extension Office and you will soon get a response back.
Friday, July 31, 2009
Tuesday, July 28, 2009
Turf Irrigation: What is the Best Time?
Cities throughout Central Texas are struggling through one of the most devastating droughts in our lifetimes. Agriculture losses are already at $3.6 billion and that does not include the loss in landscape plants and turfgrasses. Cities in this area have two major concerns, number one being the amount of water needed to supply all the people with clean drinking water and number two having enough system capacity to meet the extremely high demand during all these hot days.
Fortunately most cities have enough water, if we conserve, to get us through this hot summer. During cooler times when landscapes don’t need as much water we see both the aquifers and lakes stabilize and who knows maybe we will get some rain soon. The other problem, having enough capacity, is simply of function of when we water our turfgrasses! There is no doubt that most people have learned to water turfgrasses early in the morning so that the grass has time to dry out to prevent diseases. Every city water department can testify to how well we know this by the amount of water used during the 3 AM to 7 AM time period. It seems as if every sprinkler system in the city fires up during this time and the consequent drop in pressure for the city water system frustrates even the best water department managers.
So you may have been notified by your city water department of voluntary changes to your watering schedule. Of course most cities want you to avoid watering in the hottest, windiest times of day, usually 10 AM to 6 PM. But to avoid over taxing the system you may be asked to change your irrigation times to 8 PM at night or 7 AM in the morning or even midnight! Almost everyone who hears of these changes immediately worries that they will cause lawns to get diseases and die or that all the water will evaporate before it hits the ground. Nothing could be further from the truth. In the hot summer time we just don’t have the conditions, night or day, for turfgrass diseases to develop because of irrigation. The grass dries too quickly for disease to develop. And being so hot, even at night, we see very little difference in irrigation evaporation - morning, evening or night. Currently evapotranspiration rates are running around .25 inches of water per day. Looking at the data the real increase in evapotranspiration rates is not the time of day you water but whether there is wind or not. Rates can increase 50% or more with just 10 mph winds!
Next there is some confusion on how much to water? It is really quite simple, all turfgrasses need 1 inch or less of water per week, period! In looking at the area’s soils and knowing the turfgrass water requirements based on evapotranspiration we actually only need ¾ of an inch a week to maintain a beautiful green lawn. The next question is how many minutes do I set my sprinkler system to water ¾ inch. Set out empty tuna cans around your lawn, water until they are nearly 1/2 full and do this twice a week and you will have given your lawn more than enough water to be beautiful!
Now what is the take home message? Just this, follow the city’s water schedule and watch how much water you use and you won’t hurt your landscape but you will help us all get through these tough times.
Fortunately most cities have enough water, if we conserve, to get us through this hot summer. During cooler times when landscapes don’t need as much water we see both the aquifers and lakes stabilize and who knows maybe we will get some rain soon. The other problem, having enough capacity, is simply of function of when we water our turfgrasses! There is no doubt that most people have learned to water turfgrasses early in the morning so that the grass has time to dry out to prevent diseases. Every city water department can testify to how well we know this by the amount of water used during the 3 AM to 7 AM time period. It seems as if every sprinkler system in the city fires up during this time and the consequent drop in pressure for the city water system frustrates even the best water department managers.
So you may have been notified by your city water department of voluntary changes to your watering schedule. Of course most cities want you to avoid watering in the hottest, windiest times of day, usually 10 AM to 6 PM. But to avoid over taxing the system you may be asked to change your irrigation times to 8 PM at night or 7 AM in the morning or even midnight! Almost everyone who hears of these changes immediately worries that they will cause lawns to get diseases and die or that all the water will evaporate before it hits the ground. Nothing could be further from the truth. In the hot summer time we just don’t have the conditions, night or day, for turfgrass diseases to develop because of irrigation. The grass dries too quickly for disease to develop. And being so hot, even at night, we see very little difference in irrigation evaporation - morning, evening or night. Currently evapotranspiration rates are running around .25 inches of water per day. Looking at the data the real increase in evapotranspiration rates is not the time of day you water but whether there is wind or not. Rates can increase 50% or more with just 10 mph winds!
Next there is some confusion on how much to water? It is really quite simple, all turfgrasses need 1 inch or less of water per week, period! In looking at the area’s soils and knowing the turfgrass water requirements based on evapotranspiration we actually only need ¾ of an inch a week to maintain a beautiful green lawn. The next question is how many minutes do I set my sprinkler system to water ¾ inch. Set out empty tuna cans around your lawn, water until they are nearly 1/2 full and do this twice a week and you will have given your lawn more than enough water to be beautiful!
Now what is the take home message? Just this, follow the city’s water schedule and watch how much water you use and you won’t hurt your landscape but you will help us all get through these tough times.
Lawn Aerification to Help Watering
In this terrible drought it is not unusual to hear people complain that even though they are watering the water just seems to run off. Or when they do irrigate the water just seems to puddle on the soil surface taking forever to move down. Both these problems have to do with water infiltration or movement into soils and with our heavy, clay soils in Central Texas. These soils give us lots of problems with infiltration and when water doesn’t move into our soils our lawns suffer from drought and we ultimately waste water.
Compaction is usually identified as the main culprit to slow water movement into soils. Heavy, clay soils are notorious for developing compaction especially since we are constantly passing heavy mowers over them and having to water so much with sprinklers. It is not unusual to see lawn services using large mowers that support a driver. This weight passing over the soil once or twice a week, especially soil that is wet, forms hard compacted layers that water simply can’t pass through. Next add in sprinklers that come on 3 times a week further compacting soils with water that contains high levels of calcium and it is no wonder why we have trouble watering our landscapes.
Because compaction can be such a problem it is a standard recommendation by Texas A&M turf experts to aerify soils once a year with a core aerifier. What this machine does is take a plug out of the turf opening up a hole for water and oxygen to pass through quickly. Once water is in the hole it moves sideways into the turf root zone for more complete irrigation. Sometimes lawn services will fill the holes with an organic amendment which only helps turf with fertilizer and water movement.
When is the best time to aerify? Usually it is recommended for spring time, just as grasses are greening up. Unfortunately there is no way to get every lawn done then but rest assured aerification yields a benefit no matter when you do it!
Compaction is usually identified as the main culprit to slow water movement into soils. Heavy, clay soils are notorious for developing compaction especially since we are constantly passing heavy mowers over them and having to water so much with sprinklers. It is not unusual to see lawn services using large mowers that support a driver. This weight passing over the soil once or twice a week, especially soil that is wet, forms hard compacted layers that water simply can’t pass through. Next add in sprinklers that come on 3 times a week further compacting soils with water that contains high levels of calcium and it is no wonder why we have trouble watering our landscapes.
Because compaction can be such a problem it is a standard recommendation by Texas A&M turf experts to aerify soils once a year with a core aerifier. What this machine does is take a plug out of the turf opening up a hole for water and oxygen to pass through quickly. Once water is in the hole it moves sideways into the turf root zone for more complete irrigation. Sometimes lawn services will fill the holes with an organic amendment which only helps turf with fertilizer and water movement.
When is the best time to aerify? Usually it is recommended for spring time, just as grasses are greening up. Unfortunately there is no way to get every lawn done then but rest assured aerification yields a benefit no matter when you do it!
Thursday, July 2, 2009
Drip Irrigation, Water When the Plants Need It
I am constantly amazed at how few people use drip irrigation for their gardens, shrubs or flower beds. Most people avoid new technology like the plague but drip irrigation has been around for decades and now installation is easier than ever. Remember it’s about water savings but probably more important for this fast paced world it’s labor saving too.
The basic component parts of a drip irrigation system are: water source (well or city), filter, pressure regulator, delivery lines and emitters. The filter is a must if you have a well but not a high priority with city water so that a $5 filter is fine. The pressure regulator allows the lines and emitters to operate at low pressure (10-25 lbs) so that very little water comes out at a time. Depending on the type of emitter, we are talking about 0.5-2 gallons per hour per emitter. The lines are black poly pipe easily joined together with low pressure fittings since we use low water pressure. The emitters can be punched into the poly pipe wherever you have a plant or for vegetable gardens you can use drip irrigation tape that is thin walled and the emitters are already molded into it.
The place to start is with a knowledgeable salesperson. He can help you know what parts to buy and the best material to buy. Once you purchase the parts you simply start at the faucet or hose end with your filter and pressure regulator. The poly pipe is laid to your first plant and an emitter is punched in and the poly pipe goes on to the next plants until all are covered by the system. The poly can be buried in the ground or under mulch for easy repairs. For real labor savings install a timer at the faucet and leave the watering to the system. It’s easy and fun so why not give it a try.
Drought Continues to Linger
A simple drive around Williamson County and you easily tell that we are in a drought. West of I35 the drought has been so long and so severe that we are losing cedar trees along with oaks and cedar elm. Pastures have produced a small hay crop with the potential for more hay cuttings dwindling daily in the heat and wind. On the east side of I35 in the Blackland crops, a majority of the corn acres are all but gone in this hot, dry weather. Some areas have received spotty showers but overall corn is suffering or has died with very little ear production. Sorghum and cotton both are drought tolerant and they are holding their own but without rain soon even they will be gone with little if any production. Most hay producers did get one hay cutting but the yields were down and there has not been any growth for a second hay cutting. Currently hay prices are up and with most of the state still in the drought prices will continue to be high. Add to this that all livestock prices are low and you don’t have a good scenario for livestock producers in 2009. Too expensive to feed and too cheap to sell!
Lastly our landscapes are not without problems as well even though we have irrigation. Most trees and to some extent shrubs are not heavily watered and because of this they are showing extreme stress or death. Lawns have to be watered weekly or they brown quickly and most people report that turf growth has slowed significantly unless watered constantly. If this isn’t enough with the lack of rainfall we can expect to see our four legged friends return in abundance to our landscapes because there just isn’t enough to eat out in the wild. Hunger will help them overcome their fear of humans real quick and a tasty landscape is sure inviting!
So what can we say except Pray for Rain!
The basic component parts of a drip irrigation system are: water source (well or city), filter, pressure regulator, delivery lines and emitters. The filter is a must if you have a well but not a high priority with city water so that a $5 filter is fine. The pressure regulator allows the lines and emitters to operate at low pressure (10-25 lbs) so that very little water comes out at a time. Depending on the type of emitter, we are talking about 0.5-2 gallons per hour per emitter. The lines are black poly pipe easily joined together with low pressure fittings since we use low water pressure. The emitters can be punched into the poly pipe wherever you have a plant or for vegetable gardens you can use drip irrigation tape that is thin walled and the emitters are already molded into it.
The place to start is with a knowledgeable salesperson. He can help you know what parts to buy and the best material to buy. Once you purchase the parts you simply start at the faucet or hose end with your filter and pressure regulator. The poly pipe is laid to your first plant and an emitter is punched in and the poly pipe goes on to the next plants until all are covered by the system. The poly can be buried in the ground or under mulch for easy repairs. For real labor savings install a timer at the faucet and leave the watering to the system. It’s easy and fun so why not give it a try.
Drought Continues to Linger
A simple drive around Williamson County and you easily tell that we are in a drought. West of I35 the drought has been so long and so severe that we are losing cedar trees along with oaks and cedar elm. Pastures have produced a small hay crop with the potential for more hay cuttings dwindling daily in the heat and wind. On the east side of I35 in the Blackland crops, a majority of the corn acres are all but gone in this hot, dry weather. Some areas have received spotty showers but overall corn is suffering or has died with very little ear production. Sorghum and cotton both are drought tolerant and they are holding their own but without rain soon even they will be gone with little if any production. Most hay producers did get one hay cutting but the yields were down and there has not been any growth for a second hay cutting. Currently hay prices are up and with most of the state still in the drought prices will continue to be high. Add to this that all livestock prices are low and you don’t have a good scenario for livestock producers in 2009. Too expensive to feed and too cheap to sell!
Lastly our landscapes are not without problems as well even though we have irrigation. Most trees and to some extent shrubs are not heavily watered and because of this they are showing extreme stress or death. Lawns have to be watered weekly or they brown quickly and most people report that turf growth has slowed significantly unless watered constantly. If this isn’t enough with the lack of rainfall we can expect to see our four legged friends return in abundance to our landscapes because there just isn’t enough to eat out in the wild. Hunger will help them overcome their fear of humans real quick and a tasty landscape is sure inviting!
So what can we say except Pray for Rain!
Spider Mites on Tomatoes
It didn’t take long for spider mites to attack tomatoes and attack with a passion. I have had a number of calls about tomatoes that are turning yellow and in most cases it is spider mites that are the culprit.
The two spotted spider mite is responsible for most of our tomato problems. They are very small at 1/32 of an inch or less. If you turn over a tomato leaf you will see the webbing characteristic of spider mites and if you look closer you may see the actual mite moving around. Spider mites overwinter as adults and even continue to breed on host plants in mild winters. Spider mite adults lay a clear to yellow egg suspended in a fine web of silk. 6-legged nymphs emerge from the eggs and go through 2 molts before they emerge as 8-legged adults. A generation can last from 5 to 20 days depending on the temperature, the hotter the quicker. When the host plant begins to decline, the mites spin silk threads and use these strands to “fly” or “balloon” in wind to disperse to other plants. This is how they get to your tomatoes in the first place.
Scouting is essential to control. If you see spider mites early you can wash them off with hard streams of water or use an insecticidal soap. Sulphur has long been used as a preventative for mites as well as a fungicide for diseases. Garlic has been promoted but my experience has not been good. Unfortunately most gardeners do not notice infestations until they are severe and control is difficult. The chemical Malathion is labeled and tomatoes can be picked after waiting one day. Other chemicals are much better for killing the mites but unfortunately you must wait anywhere from 3 to 14 days before harvest. I like to recommend that gardeners remove the plants that are infested. This may seem drastic but letting populations explode doesn’t seem healthy either.
Lastly let me add that spider mites love plants that are stressed, especially from water. I was recently running a greenhouse experiment with tomatoes and marigolds. I had many pots of each and I had inadvertently left some of both plants almost outside the area that was sprinkled. This meant that 2 tomato plants and 2 marigold plants were getting just enough water to live but not much else. I then went on vacation for a few days and when I came back the only spider mite infested plants were those stressed for water. To back up my hypothesis, I water my vegetable garden every day for several hours and so far no spider mites!
The two spotted spider mite is responsible for most of our tomato problems. They are very small at 1/32 of an inch or less. If you turn over a tomato leaf you will see the webbing characteristic of spider mites and if you look closer you may see the actual mite moving around. Spider mites overwinter as adults and even continue to breed on host plants in mild winters. Spider mite adults lay a clear to yellow egg suspended in a fine web of silk. 6-legged nymphs emerge from the eggs and go through 2 molts before they emerge as 8-legged adults. A generation can last from 5 to 20 days depending on the temperature, the hotter the quicker. When the host plant begins to decline, the mites spin silk threads and use these strands to “fly” or “balloon” in wind to disperse to other plants. This is how they get to your tomatoes in the first place.
Scouting is essential to control. If you see spider mites early you can wash them off with hard streams of water or use an insecticidal soap. Sulphur has long been used as a preventative for mites as well as a fungicide for diseases. Garlic has been promoted but my experience has not been good. Unfortunately most gardeners do not notice infestations until they are severe and control is difficult. The chemical Malathion is labeled and tomatoes can be picked after waiting one day. Other chemicals are much better for killing the mites but unfortunately you must wait anywhere from 3 to 14 days before harvest. I like to recommend that gardeners remove the plants that are infested. This may seem drastic but letting populations explode doesn’t seem healthy either.
Lastly let me add that spider mites love plants that are stressed, especially from water. I was recently running a greenhouse experiment with tomatoes and marigolds. I had many pots of each and I had inadvertently left some of both plants almost outside the area that was sprinkled. This meant that 2 tomato plants and 2 marigold plants were getting just enough water to live but not much else. I then went on vacation for a few days and when I came back the only spider mite infested plants were those stressed for water. To back up my hypothesis, I water my vegetable garden every day for several hours and so far no spider mites!
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