Most people don’t have a clue what budding or grafting is or if they don’t know why we do it! I can sure understand this since most of the reproduction in the world on the human side is not asexual it is sexual. Wow! How did we go from budding and grafting to SEX? Well in budding and grafting we bypass the typical crossing of a male and a female to produce offspring by either budding or grafting a portion of the plant we want onto the same type of plant. For instance, in pecan trees the nut that is produced can be planted by a squirrel and grow up into a big beautiful pecan tree but the nuts on that tree may not resemble the planted nut at all. This is because the nut was produced by sexual means. The male pollen was produced on another tree and it floated on the wind and fell on the pecan tree flower of another tree. Once on the flower parts, the male and female parts mate and the resulting nut now has the genetics of the male tree crossed with the female tree. As any parent knows our children may or may not be like us! In nature this natural crossing produces what we know as native pecans.
Now in budding and grafting we bypass this uncertainty by taking a bud or a piece of graftwood with buds from a tree we like and transfer these buds onto a tree or rootstock that produces poor quality nuts. This is an asexual method which reproduces exactly the nuts we want. This is also used on all our fruit trees as well as our nut trees. Basically we can use either buds or grafts depending on the tree type, personal preference or tree size. Most nurseries growing small trees use single buds called budding and in orchards we use grafting which is putting a small limb with several buds onto a tree.
Having said all this there are still many people who grow pecans but very few that have ever grafted one! If you are in this category then you won’t want to miss the Pecan Grafting Workshop set for Tuesday, April 21 at the Extension Meeting Room. The real work will start at 7:00 p.m. and will go on till you have perfected your grafting technique. Local pecan growers with years and years of experience will be your teachers and in this hands on workshop you can learn to graft both the inlay bark graft and the four flap graft. Plus if you would like to learn other techniques as well there will be Extension bulletins and experts to discuss how they are done. Also it is our hope to have some pecan graftwood available but supplies are limited in this drought year. If you would like to attend the grafting workshop then call the Extension office at 512/943-3300 to reserve a spot.
Monday, April 20, 2009
Monday, April 6, 2009
Fruit Tree Insect and Diseases
I think we can blame the drought for causing another problem, terrible insect pressure especially on our fruit trees. Most if not all fruit trees have made it through the winter, and most have survived the drought, if you watered. They have made it through freezes and most have small fruit, no small miracle for Texas fruit production! Now after making it through all these problems we have one more to add to the list, stink bugs!
Both the brown stink bug and the green stink bug overwinter in grassy areas and under brush or wood. They wait for warm weather to come out and begin looking for energy sources to replace lost body reserves and the plant of choice is fruit. The brown stink bug causes the fruit to deform and the green stink bug causes the fruit to exude a resin or gummy mess that can accumulate on the fruit especially on peaches. Both insects have long snouts that they use to pierce the skin and suck out juices. In the case of the green stink bug this resin attracts wasps and bees so that they get the blame instead of the stink bug. Stink bugs are hard to control especially since they have piercing/sucking mouthparts. Carbaryl or permethrins are two of the most effective inorganic chemicals but for organic growers your only choice is neem oil and its effectiveness is not good
There is one major peach insect that everyone wants to get rid of, the Plum Curculio. This small worm or grub feeds inside the peach mostly near the seed and can cause anyone who has found one a real heartache. This worm or larva is laid by an adult snout beetle, similar in looks to the oak, pecan or cotton weevil. This adult overwinters in the soil at the base of the fruit tree and comes out early with the plums and moves to peaches as plums mature early. The adult female will chew a small hole in the fruit skin and lay eggs just under the surface. The eggs hatch into small larva that feed in the fruit for 2 to 4 weeks and of course this is what causes the problems.
To control this insect sprays have to be made from shucksplit (about the time the fruit is formed) and for two applications at two week intervals and then 30 days before fruit harvest. This last spray is probably the most important since the eggs laid hatch out and the larva are still in the fruit at harvest. Recommended sprays are malathion, carbaryl or permethrin and organic is garlic and citrus oil, and neem oil to repel the adults. There is no insecticide to treat the soil with but keeping old fruit off the ground helps prevent next year’s problems.
Another problem some homeowners have complained about is the gummy mess coming out of fruit tree limbs. This gum or resin is caused by a bacterial canker that has infected the limb. This canker develops in the fall and as the trees break dormancy in the spring, gum is formed by the infection and can break through the bark and flow down the tree limb. Stress in trees is the main culprit and treatments are not effective. Keep damaged wood trimmed out and supply water and nutrients to promote tree health.
Both the brown stink bug and the green stink bug overwinter in grassy areas and under brush or wood. They wait for warm weather to come out and begin looking for energy sources to replace lost body reserves and the plant of choice is fruit. The brown stink bug causes the fruit to deform and the green stink bug causes the fruit to exude a resin or gummy mess that can accumulate on the fruit especially on peaches. Both insects have long snouts that they use to pierce the skin and suck out juices. In the case of the green stink bug this resin attracts wasps and bees so that they get the blame instead of the stink bug. Stink bugs are hard to control especially since they have piercing/sucking mouthparts. Carbaryl or permethrins are two of the most effective inorganic chemicals but for organic growers your only choice is neem oil and its effectiveness is not good
There is one major peach insect that everyone wants to get rid of, the Plum Curculio. This small worm or grub feeds inside the peach mostly near the seed and can cause anyone who has found one a real heartache. This worm or larva is laid by an adult snout beetle, similar in looks to the oak, pecan or cotton weevil. This adult overwinters in the soil at the base of the fruit tree and comes out early with the plums and moves to peaches as plums mature early. The adult female will chew a small hole in the fruit skin and lay eggs just under the surface. The eggs hatch into small larva that feed in the fruit for 2 to 4 weeks and of course this is what causes the problems.
To control this insect sprays have to be made from shucksplit (about the time the fruit is formed) and for two applications at two week intervals and then 30 days before fruit harvest. This last spray is probably the most important since the eggs laid hatch out and the larva are still in the fruit at harvest. Recommended sprays are malathion, carbaryl or permethrin and organic is garlic and citrus oil, and neem oil to repel the adults. There is no insecticide to treat the soil with but keeping old fruit off the ground helps prevent next year’s problems.
Another problem some homeowners have complained about is the gummy mess coming out of fruit tree limbs. This gum or resin is caused by a bacterial canker that has infected the limb. This canker develops in the fall and as the trees break dormancy in the spring, gum is formed by the infection and can break through the bark and flow down the tree limb. Stress in trees is the main culprit and treatments are not effective. Keep damaged wood trimmed out and supply water and nutrients to promote tree health.
Zinc is Essential for Pecans
In the Texas Pecan Handbook, John Begnaud, Extension Horticulturalist writes that, “Over 40 years of pecan zinc research confirms that the pecan tree is a poor accumulator and transporter of zinc, especially when grown in high pH soils.” Any commercial pecan grower in the state can testify that this statement is true and none of them will miss a zinc spray unless it rains. Unfortunately many new growers and perhaps some in the business a long time forget how important zinc is in pecan growth.
What does zinc do? Well zinc is necessary for the production of natural plant hormones that induce cell elongation and cell division or better said overall plant growth. In our high pH soils we can have lots of zinc but little of it is available to the tree and so we see deficiency symptoms such as small, narrow leaves. These leaves are usually on thin shoots with very short internodes. When you only have small leaves and possibly less leaves then you don’t produce pecans or a smaller crop than expected. Continual zinc deficiencies can result in bunchy terminal growth and even some canopy die-back. Dr. George Ray McEachern, pecan specialist, describes zinc deficiencies as small leaves that curve, leaf edges waxy, leaves with dark interveinal discoloration, shoots growing in thick bunches with some dead some alive.
Now what do we mean by zinc applications? In the many research trials that have been done the only effective and efficient way to get zinc into a pecan tree is foliar applications. Over the years soil injections, tree injections and fertilizer applications have all been tried but still foliar applications are the best. Unfortunately our high pH soils very quickly make and soil applications of zinc bound up and unavailable. Tree injections move zinc to existing growth but since zinc is immobile in the plant the new growth doesn’t get the benefit. This unique set of circumstances forces growers to make repeated foliar applications to new growth to ensure adequate zinc uptake in pecan leaves.
Another aspect of the zinc research in pecans is the best formulations for zinc uptake. To date three compounds have been the most effective, zinc sulphate, zinc nitrate and NZN. Of these three the most widely used is zinc sulphate probably because it is just as effective as the other two but is cheaper. Another part of this research has shown that the effectiveness of zinc uptake is enhanced by the addition of liquid nitrogen in the tank. It doesn’t take much zinc or liquid nitrogen, only 2 lbs of zinc sulphate and 1 quart of liquid N per 100 gallons of water. For homeowners there are numerous products on nursery shelves for zinc applications and all work well. Use a hose-end sprayer to reach tree tops.
Now the hard part is getting the trees sprayed on a timely basis. Remember that zinc is not translocated so a grower needs to make regular sprays during the spring flush. The first spray should be at green tip or what we call budbreak, then 1-2 weeks later followed by another 1-2 weeks later or with casebearer insect sprays and then one more 2-3 weeks later. Pecan growth is fairly mature by mid-June so that sprays can be discontinued on all but young trees which should be sprayed until August.
Of all the things you can do to a pecan tree to help make pecans there is probably nothing more important than zinc sprays and now is the time to get started!
What does zinc do? Well zinc is necessary for the production of natural plant hormones that induce cell elongation and cell division or better said overall plant growth. In our high pH soils we can have lots of zinc but little of it is available to the tree and so we see deficiency symptoms such as small, narrow leaves. These leaves are usually on thin shoots with very short internodes. When you only have small leaves and possibly less leaves then you don’t produce pecans or a smaller crop than expected. Continual zinc deficiencies can result in bunchy terminal growth and even some canopy die-back. Dr. George Ray McEachern, pecan specialist, describes zinc deficiencies as small leaves that curve, leaf edges waxy, leaves with dark interveinal discoloration, shoots growing in thick bunches with some dead some alive.
Now what do we mean by zinc applications? In the many research trials that have been done the only effective and efficient way to get zinc into a pecan tree is foliar applications. Over the years soil injections, tree injections and fertilizer applications have all been tried but still foliar applications are the best. Unfortunately our high pH soils very quickly make and soil applications of zinc bound up and unavailable. Tree injections move zinc to existing growth but since zinc is immobile in the plant the new growth doesn’t get the benefit. This unique set of circumstances forces growers to make repeated foliar applications to new growth to ensure adequate zinc uptake in pecan leaves.
Another aspect of the zinc research in pecans is the best formulations for zinc uptake. To date three compounds have been the most effective, zinc sulphate, zinc nitrate and NZN. Of these three the most widely used is zinc sulphate probably because it is just as effective as the other two but is cheaper. Another part of this research has shown that the effectiveness of zinc uptake is enhanced by the addition of liquid nitrogen in the tank. It doesn’t take much zinc or liquid nitrogen, only 2 lbs of zinc sulphate and 1 quart of liquid N per 100 gallons of water. For homeowners there are numerous products on nursery shelves for zinc applications and all work well. Use a hose-end sprayer to reach tree tops.
Now the hard part is getting the trees sprayed on a timely basis. Remember that zinc is not translocated so a grower needs to make regular sprays during the spring flush. The first spray should be at green tip or what we call budbreak, then 1-2 weeks later followed by another 1-2 weeks later or with casebearer insect sprays and then one more 2-3 weeks later. Pecan growth is fairly mature by mid-June so that sprays can be discontinued on all but young trees which should be sprayed until August.
Of all the things you can do to a pecan tree to help make pecans there is probably nothing more important than zinc sprays and now is the time to get started!
Sunday, March 15, 2009
Chilling Accumulation: Its Importance and Estimation
This year we have had what has seemed like an unusually warm winter. In actuality it has been really cool overall with average temperatures in December being 51.3 degrees, in January 50.6 degrees and February being a cold 58.8 degrees. I get a lot of questions about chilling hours and if we have accumulated enough. Stone fruit trees such as peaches develop their vegetative and fruiting buds in the summer and, as winter approaches, the already developed buds go dormant in response to both shorter day lengths and cooler temperatures. This dormancy or sleeping stage protects these buds from oncoming cold weather. Once buds have entered dormancy, they will be tolerant to temperatures much below freezing and will not grow in response to mid-winter warm spells. These buds remain dormant until they have accumulated sufficient chilling units (CU) of cold weather. Almost any variety of stone fruit you buy will have its chilling requirement on the tag. When enough chilling accumulates, the buds are ready to grow in response to warm temperatures. As long as there have been enough CU’s the flower and leaf buds develop normally. If the buds do not receive sufficient chilling temperatures during winter to completely release dormancy, trees will develop one or more of the physiological symptoms associated with insufficient chilling: 1) delayed foliation, 2) reduced fruit set and increased buttoning and, 3) reduced fruit quality.
Delayed Foliation - A classic symptom of insufficient chilling is delayed leafing out. A tree may have a small tuft of leaves near the tips of the stems and have no leaves for 12 to 20 inches below the tips. Lower buds will break eventually but full foliation is significantly delayed, fruit set is reduced, and the tree is weakened.
Reduced Fruit Set and Buttoning - Flowering, in response to insufficient chilling, often follows the pattern seen with leaf development. Bloom is delayed, extended, and due to abnormalities in pistil and pollen development, fruit set is reduced. In many peach cultivars, flowers drop before or around shuck split, but in others such as ‘Jersey Queen’ and ‘Harvester’, buttons form. Buttons result from flowers which apparently have set but never develop into full-size fruit. The fruit remains small and misshapen as they ripen. If you cut these fruit open, the seed is dead.
Reduced Fruit Quality - The effects of insufficient chilling on fruit quality are probably the least discussed but appear to be very common especially in central and south Texas. The effects on leaf growth and fruit set are dramatic but the effects of insufficient chill on fruit quality are subtle, and can occur when other symptoms do not. Insufficient chilling will cause many cultivars to have an enlarged tip and reduced firmness. Furthermore, fruit ground coloration may be greener than usual, possibly due to the fruit losing firmness before the ground color can fully change from green to yellow. The extent of these quality problems depends on the cultivar and the degree of chilling deficiency.
Mean Temperature Model - The mean temperature model uses mean winter (December and/or January) monthly temperatures to estimate accumulated chilling units. The Stone Fruit Breeding Program at Texas A&M University developed a method to estimate chill accumulation which has demonstrated to be accurate for estimating chill accumulation in Texas from the Lower Rio Grande Valley up to the Red River. The coldest month or months are used for the calculation. In low chill regions (regions where average January temperature is 59-63 degrees F) where January represents the dormancy season, January mean temperature is most accurate for estimation. In high chill regions (regions where average January temperature is below 48 degrees F) a mean December-January temperature is recommended. For Williamson County we would use the December-January temperature model.
Also, this method will make it possible for the grower to know, before fruit thinning time, if chill accumulation was sufficient for a given cultivar. If insufficient chilling is suspected for a cultivar, the grower can implement management and marketing strategies to reduce the impact on costs and labor. Furthermore, chemical sprays such as Dormex that help break dormancy are being researched. These chemicals can be used in late January or early February if insufficient chilling is suspected. On the other hand, the expense of a dormancy-breaking chemical can be avoided if the grower knows that trees have received sufficient chill accumulation.
Williamson County Example
Mean December, 2008 temperature is 51.3°F and mean January, 2009 temperature is 50.6°F
Chilling Units = 4280 minus 68.8 X [(Dec. mean + Jan. mean)/2]
Chilling Units = 4280 - 68.8 X [(51.3° + 50.6°)/2]
Chilling Units = 4280 - 68.8 X 50.95
Chilling Units = 4280 - 3505.36
Chilling Units = 774.64
We normally recommend trees with 600 to 800 hour requirements and sure enough we have had enough chilling hours.
Delayed Foliation - A classic symptom of insufficient chilling is delayed leafing out. A tree may have a small tuft of leaves near the tips of the stems and have no leaves for 12 to 20 inches below the tips. Lower buds will break eventually but full foliation is significantly delayed, fruit set is reduced, and the tree is weakened.
Reduced Fruit Set and Buttoning - Flowering, in response to insufficient chilling, often follows the pattern seen with leaf development. Bloom is delayed, extended, and due to abnormalities in pistil and pollen development, fruit set is reduced. In many peach cultivars, flowers drop before or around shuck split, but in others such as ‘Jersey Queen’ and ‘Harvester’, buttons form. Buttons result from flowers which apparently have set but never develop into full-size fruit. The fruit remains small and misshapen as they ripen. If you cut these fruit open, the seed is dead.
Reduced Fruit Quality - The effects of insufficient chilling on fruit quality are probably the least discussed but appear to be very common especially in central and south Texas. The effects on leaf growth and fruit set are dramatic but the effects of insufficient chill on fruit quality are subtle, and can occur when other symptoms do not. Insufficient chilling will cause many cultivars to have an enlarged tip and reduced firmness. Furthermore, fruit ground coloration may be greener than usual, possibly due to the fruit losing firmness before the ground color can fully change from green to yellow. The extent of these quality problems depends on the cultivar and the degree of chilling deficiency.
Mean Temperature Model - The mean temperature model uses mean winter (December and/or January) monthly temperatures to estimate accumulated chilling units. The Stone Fruit Breeding Program at Texas A&M University developed a method to estimate chill accumulation which has demonstrated to be accurate for estimating chill accumulation in Texas from the Lower Rio Grande Valley up to the Red River. The coldest month or months are used for the calculation. In low chill regions (regions where average January temperature is 59-63 degrees F) where January represents the dormancy season, January mean temperature is most accurate for estimation. In high chill regions (regions where average January temperature is below 48 degrees F) a mean December-January temperature is recommended. For Williamson County we would use the December-January temperature model.
Also, this method will make it possible for the grower to know, before fruit thinning time, if chill accumulation was sufficient for a given cultivar. If insufficient chilling is suspected for a cultivar, the grower can implement management and marketing strategies to reduce the impact on costs and labor. Furthermore, chemical sprays such as Dormex that help break dormancy are being researched. These chemicals can be used in late January or early February if insufficient chilling is suspected. On the other hand, the expense of a dormancy-breaking chemical can be avoided if the grower knows that trees have received sufficient chill accumulation.
Williamson County Example
Mean December, 2008 temperature is 51.3°F and mean January, 2009 temperature is 50.6°F
Chilling Units = 4280 minus 68.8 X [(Dec. mean + Jan. mean)/2]
Chilling Units = 4280 - 68.8 X [(51.3° + 50.6°)/2]
Chilling Units = 4280 - 68.8 X 50.95
Chilling Units = 4280 - 3505.36
Chilling Units = 774.64
We normally recommend trees with 600 to 800 hour requirements and sure enough we have had enough chilling hours.
Sunday, March 8, 2009
Time to Get Those Lawns in Shape
With all the warm weather lately people are ready to start fixing up their landscapes and I am right there with them. I always start off like a fireball but like everyone else, come July I am ready for winter again!! But since spring is here let’s talk about lawn care, probably the biggest plant you have in your landscape and certainly the one that takes the most time.
First off, now is the time to get your lawn mower running again. Certainly it needs the perennial oil change and maybe a new spark plug and for sure some new gas. Fortunately gas is cheaper now than last summer. Once your mower is ready you should mow your lawn as short as you can get it. Now this may be messy but mowing it short will help warm the soil and probably more importantly take out a lot of those winter weeds or at least set them back. Some people call the procedure scalping but I don’t see many mowers that can be set low enough to actually scalp a lawn. I just call this a spring clean-up.
Next you will need to fertilize but only if you have bermudagrass or St. Augustinegrass. These two are already trying to green up telling us that soil temperatures are getting warmer by the day. Since they are starting to grow they are the ones that will respond to fertilizer the best and no matter what you hear the fertilizer they need is nitrogen. This can be the hard part because very few stores sell just a nitrogen fertilizer, either organic or inorganic. But fertilizers that have a lot of phosphorus or potassium are not really needed in our soils and can even tie up other nutrients our grasses need. What we need is 1 pound of actual nitrogen per 1000 sq. ft. or in fertilizer terms 7 pounds of 15-0-0 or 5 pounds of 21-0-0 which is a common nitrogen fertilizer. Also at this time you can apply an iron product if you have consistently had problems with yellow St Augustinegrass. Iron sulphate or Ironite can work well to help with this problem caused by our high pH soils in Williamson County.
Now those of you with Zoysia grass or buffalograss need to wait until later in April to fertilize your grasses. Both of these are slower to start in the spring and fertilizing now can only feed the weeds and other grasses in your lawn and not the actual grass you are growing.
Another thing you need to do now is water, although I think you probably already knew that! We are in a severe drought and there is no moisture in our soils for grasses or landscape plants to start growing. It is unfortunate that we have to start off the year watering but if you expect your landscape to be ready when it finally does rain you must water now. What we want is about 4 inches of wet soil. So water until you can push a shovel in about 4 inches easily. If it doesn’t soak in fast enough then turn off the sprinkler and come back in one hour. This has been a real lesson for me this year since I moved from an area with sandy soils to one here with heavy clay. The soil is great here, and very rich but it does take time to water thoroughly.
Lastly I am getting lots of complaints about weeds and weedy grasses. Well those weeds are not summer weeds only winter weeds. They have all sprouted as a result of the rains we got the first of February or were sprouted and waiting on those rains. Now they are taking advantage of an open lawn and great weather. Earlier I mentioned mowing and this is one of the best ways to really help “restrain” these weeds. If you still have too many and want to get rid of them then you can use spot treatments with a dilute Roundup solution or with 20% vinegar just “painting them with a foam brush. If that is too slow then you might try any of the weed control products you can mix up in a sprayer. Be careful though and don’t drift over to trees or shrubs since these could also be damaged. I sure don’t recommend a weed and feed product since I have never seen homeowners be that careful to avoid flower beds and sure enough these products control flowers too!!
First off, now is the time to get your lawn mower running again. Certainly it needs the perennial oil change and maybe a new spark plug and for sure some new gas. Fortunately gas is cheaper now than last summer. Once your mower is ready you should mow your lawn as short as you can get it. Now this may be messy but mowing it short will help warm the soil and probably more importantly take out a lot of those winter weeds or at least set them back. Some people call the procedure scalping but I don’t see many mowers that can be set low enough to actually scalp a lawn. I just call this a spring clean-up.
Next you will need to fertilize but only if you have bermudagrass or St. Augustinegrass. These two are already trying to green up telling us that soil temperatures are getting warmer by the day. Since they are starting to grow they are the ones that will respond to fertilizer the best and no matter what you hear the fertilizer they need is nitrogen. This can be the hard part because very few stores sell just a nitrogen fertilizer, either organic or inorganic. But fertilizers that have a lot of phosphorus or potassium are not really needed in our soils and can even tie up other nutrients our grasses need. What we need is 1 pound of actual nitrogen per 1000 sq. ft. or in fertilizer terms 7 pounds of 15-0-0 or 5 pounds of 21-0-0 which is a common nitrogen fertilizer. Also at this time you can apply an iron product if you have consistently had problems with yellow St Augustinegrass. Iron sulphate or Ironite can work well to help with this problem caused by our high pH soils in Williamson County.
Now those of you with Zoysia grass or buffalograss need to wait until later in April to fertilize your grasses. Both of these are slower to start in the spring and fertilizing now can only feed the weeds and other grasses in your lawn and not the actual grass you are growing.
Another thing you need to do now is water, although I think you probably already knew that! We are in a severe drought and there is no moisture in our soils for grasses or landscape plants to start growing. It is unfortunate that we have to start off the year watering but if you expect your landscape to be ready when it finally does rain you must water now. What we want is about 4 inches of wet soil. So water until you can push a shovel in about 4 inches easily. If it doesn’t soak in fast enough then turn off the sprinkler and come back in one hour. This has been a real lesson for me this year since I moved from an area with sandy soils to one here with heavy clay. The soil is great here, and very rich but it does take time to water thoroughly.
Lastly I am getting lots of complaints about weeds and weedy grasses. Well those weeds are not summer weeds only winter weeds. They have all sprouted as a result of the rains we got the first of February or were sprouted and waiting on those rains. Now they are taking advantage of an open lawn and great weather. Earlier I mentioned mowing and this is one of the best ways to really help “restrain” these weeds. If you still have too many and want to get rid of them then you can use spot treatments with a dilute Roundup solution or with 20% vinegar just “painting them with a foam brush. If that is too slow then you might try any of the weed control products you can mix up in a sprayer. Be careful though and don’t drift over to trees or shrubs since these could also be damaged. I sure don’t recommend a weed and feed product since I have never seen homeowners be that careful to avoid flower beds and sure enough these products control flowers too!!
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