Thursday, December 30, 2010

Citrus Greening Hope

One of the nice things about the holidays is, you get to take time off from work, catch up on a few things and relax. Okay, strike the last part, who really gets to relax during the holidays?
I have been able to catch up on a few things though, namely a little bit of my reading. The stack of magazines and books I currently have would be a speed readers nightmare.
A couple of articles really grabbed my attention and they both pertained to Citrus Greening disease.
I was talking to somebody today from here in Charleston County (we are under quarantine for Greening) and she did not have any idea about it. I am doing a Citrus lecture for her garden club on the 11th, I think I am going to scare some of these folks.
Just to give some of you that may not know what Citrus Greening is, here is a Readers Digest version.
Huanglongbing (pronounced Hung-Long-Bing) or Yellow Dragon Disease is one of the most serious Citrus diseases. It is a bacterial disease that attacks the vascular system. Once infected, the tree will produce inedible bitter fruit, the fruit will not be able to ripen and the tree will ultimately die in a few years. There is currently no cure for the disease.
It is spread by a tiny insect known as the Asian Citrus Psyllid.
This is their feeding posture. 45 degrees to the stem. The adults are 3 to 4 mm (or 0.15748031496 inches) long with a mottled brown body. They are really very small. It only takes an infected Psyllid about 15 minutes to infect a tree.
It can also be transmitted by grafting.
The diseased leaves look like this.
This disease can be tricky to detect because it mimics many nutritional deficiencies. On the above picture, notice the non-mirrored yellowing. If this was nutritional the two sides of the leaves would be identical.
Like I said, this is an EXTREMELY short version of what Greening disease is. To find out if you are under quarantine here in the United States go to this link HERE It will tell you all you need to know.
Okay, that was your Citrus Greening mini lecture. I mentioned the two articles that grabbed my attention. The first one dealt with feeding the crap out of Greening infected trees to rejuvenate them. I guess the old cliche "Starve a cold and feed a fever" would be a good analogy here. Maury Boyd, a Citrus producer near Immokalee, Florida has successfully been applying a cocktail of nutrients to his ravaged trees. I won't go into the long list of what he is applying, but it is done three times a year just after each new flush of growth.
There is still many tests being performed on this treatment. The article goes on to say that Mr. Boyd is pleased with the overall health of his grove, he would have plowed them under before trying this method, and the fruit yields have met or exceeded industry average. Fruit quality has also improved.
I am not telling you to go out and start pouring all kinds of fertilizers on your trees, like I said, there is still MUCH research to do here.
The other article I mentioned will undoubtedly cause controversy. The title is "Genetic Engineering Tackles Citrus Greening". There was a lot of scientific mumbo jumbo, but I got the gist of it. Basically, to save the 9.3 billion dollar annual economic benefit to Florida, there may have to be some playing around with the genes of Citrus. The article also states that groups that are opposed to genetically modified foods of any kind may try to dissuade the public from turning to genetically engineered Orange Juice. It's not like they are trying to create a Frankenstein Orange, they have discovered that there are some genes in Spinach that may provide some resistance. They don't have a complete handle on all this yet, but it is in research. I, for one, have no problem with Genetically Modified Food or GMO's, though I am not sure if my Orange Juice had the aftertaste of Spinach, it would be all that great! Ha-Ha
This has been a VERY brief overview of what these articles said, both were 3+ pages long. I just wanted to show you that there is research going on to fix this horrible disease to Citrus. I remember just a couple of years ago there was a notion going around Florida that if something wasn't done soon the whole Citrus industry could be wiped out in 5-10 years! A very sobering thought.
One last thing I would like to mention. I know they have a huge stake in the Orange Juice industry, but if their OJ sales stopped they would not go bankrupt. I would like to THANK Coca-Cola for their 1.5 million dollar donation to research for finding a cure for HLB (Huanglongbing). Hopefully someday they will find one!
Happy Growing!

Sunday, December 19, 2010

Cold Damage Identification and What to DO about it

The past month or so, I have made numerous blog postings about bringing in your plants and protecting them from the Winter weather. If you missed either of these postings, you can read it HERE and HERE .
Today I am going to talk to the people that, for one reason or another, didn't bring their plants in or try to protect them. They may have missed the weather report, forgot about their plants, or didn't want to take the time to do it and now their significant other is upset because the plant looks dead. There may be hope!
You will need to ask and answer a couple of questions: How cold was the temperature? How long was the plant exposed? What was the health of the plant before the damage?
First, let's take a quick look at what cold weather is and how it can affect plants. I know, duh, it's cold, they freeze! Well, just follow me for a minute.
The sun warms the soil surface during the day; the heat is then radiated into the cool atmosphere during the night. The coldest temperatures occur about daybreak.
Clouds at night can absorb and reflect heat back to the earth.
Calm, clear nights pose the greatest danger of frost since there is no wind to mix the ascending warm air with the descending cold air, and no clouds to radiate heat back to the soil.
Cold air settles downward, flowing like water,to the lowest point. Hot air rises.
The effects of temperature vary with plant species, stage of growth, age, general health and water content. Young, actively growing, flowering, and/or dehydrated plants tend to be most vulnerable.
Freezing temperatures damage plants by rupturing plant cells as ice crystals form and rapid changes in temperatures occur. Evergreen plants can suffer damage from blowing Winter winds and dry out when water is unavailable from ground that is frozen. Chilling injury can occur to many tropical plants although temperatures do not drop below 32 degrees.
The signs of cold damage can be confusing, since some damage may not be evident until months later. Leaves and tender shoots subjected to freezing temperatures or chilling damage appear water soaked and wilted. These tissues will usually turn black within a few hours or days. The tips of narrow-leaved evergreens, such as junipers, may turn uniformly brown. Broad-leaved evergreens, such as hollies, often have leaf burn along their edges. Less flowering is common during the following season.
One of the main things to remember is Do NOT prune frost-damaged, woody growth until the plant begins growing in the Spring. Pruning might stimulate new growth which would be vulnerable to late frosts. The frost damaged leaves and stems will continue to help trap warm air within the canopy. This is especially true in very large leaf type plants, such as Bananas. In addition, the damage is often not nearly as bad as it initially looked, new growth may come out of tissue that you thought was dead. Once the new growth starts in the Spring, you can prune out the dead wood.
A large, deep, crack running up and down the trunk of a tree or large shrub is known as a frost crack. The crack is usually on the South or Southwest side of the trunk, but can occur on any side. Young trees or older trees with smooth bark are the most susceptible.
Frost cracks occur when the sun warms the trunk in the Winter, causing tissues to rapidly expand or when clouds or buildings block the sun. At sunset the temperature of the trunk drops quickly to that of the surrounding air, and the trunk contracts. The outer part of the trunk cools and contracts faster than the inner tissues. This difference in contraction rates can cause the outer trunk to crack. You can usually eliminate this problem by wrapping the trunks with burlap or some other type of protection, not plastic, it needs to breathe. Start at the ground and work your way up to the first branch. Prevention is important, once the crack occurs, there is not much that can be done. Such frost cracks often close and callus over during the Summer, only to reopen in following Winters. This callusing and recracking may lead to the formation of large "frost ribs" on the side of affected trees. Something else to keep in mind, insects like to find places to hide and a large split open trunk is basically a "We'll keep the light on for you" sign. You could be looking at a major infestation. Frost cracks in trees are also ideal sites for the entrance of wood decaying organisms.
Desiccation, or drying out, is a particular problem on evergreen plants. This occurs when water is leaving the plant faster than it is being taken into the plant. During the Winter months desiccation can occur if the ground is frozen beyond the depth of the root system. If the Fall has been dry, there may not be enough ground moisture available for the plant. Water loss is greatest during windy, sunny conditions. This type of injury appears as discolored or burned evergreen needles or leaves.
After a killing cold some plants may be frozen back to the ground but lower buds and roots often survive. It can take these plants months to begin growth. Give them at least the Spring months to show signs of growth. I had a Clethera that did not regrow until Summer. I had just about given up on it but it showed me how persistent plants can be.
Okay, you have this plant that has lost all its leaves, looks naked and you are figuring it is a goner. Take a look at the bark or stem, is it black, shriveled or separated from the trunk? It’s most likely beyond help if it is. Don’t look just at the top but down at the base.
Next start high and scrape a small section of the bark. If you find brown at all keep moving lower until you find green, believe me you’ll know when you find it.
When you find an area of green, cut off everything above it, on that stem or branch. When you get done going over this you may have a plant that stands a chance of coming back. This really needs to wait until Spring though.
Remember, not only was the foliage, branches and stems exposed to the cold, so were the roots. No matter how hard you try the plant may not survive. The root damage may be so severe that you’ll be fighting an uphill battle.
As much as you may love your plant, you must be realistic, It may be too far gone!
I get teased all the time about my infatuation with what the weather is doing, what it is going to do and what it has done in the past. The best remedy is to keep your eyes on the weather, bring your plants in before the cold hits, and to grow things that are suited for your climate zone.
I hope everybody has a Very Merry Christmas!
Happy Growing!

Sunday, December 12, 2010

Holy Hothouse Plantman

As any of you that have been following my blog, or have at least read some of the past postings, know, I have a greenhouse. I would be lost and in a constant state of depression without it. Where else can I go when the wind is whipping, the temperature is right around freezing, and sit around a bunch of tropical plants at 65 degrees and not leave my zip code?
I am not telling you all this to brag, but to maybe give you some ideas on what to ask for, for Christmas.
There are ALL kinds of greenhouse kits online, for all kinds of budgets. You can ask for one of those, OR, you can ask for a giftcard to a home improvement store to buy the needed supplies. I built my own from the ground up. Trust me it is not the prettiest thing in the world, actually it borders on grotesque looking, but it is functional. I promise it is not that difficult. I am nothing like my brother who is a cross between Bob Villa and McGyver, he can build anything out of anything and it be strong enough to hold a tank. Nope, I am lucky I know which end of a hammer to use.
Basically, you are building a big box with a roof and a door. As long as it is enclosed, you have a greenhouse. I am not going to get into the specifics here on how to build one, like I said there are kits online and plenty of floor plans out there. Many books with designs have also been written.
I am going to instead tell you what you need to do with that greenhouse after you unwrap it Christmas morning.
You have all heard the motto of a good business, The three things you need to succeed is location, location, location. The same holds true here. The greenhouse should be located where it gets maximum sunlight. The first choice of location is the South or the Southeast side of a building or shade tree. Sunlight all day is the best, but morning sunlight on the East side is the next best thing. I use my greenhouse primarily in the Winter, but it can be used all year round if placed in the correct spot. Deciduous trees,(trees that lose their leaves) such as Maple, can effectively shade the greenhouse from the intense late afternoon Summer sun. Deciduous trees also allow maximum exposure to the Winter sun because they do shed their leaves in the Fall. You do not want to use an evergreen tree, such as a Pine, because they will shield the greenhouse from the less intense Winter sun. Trust me, you want to capture as much of the sun at this time of year as you can. Remember that the sun is lower in the sky this time of year.
Good drainage is another requirement for the site. Yes, most of your plants will probably be on shelves, but some will not. Plus, you will not be on a shelf. If going out to the greenhouse after a heavy rain is a miserable experience, standing in the mud and muck, you are just setting yourself and your plants up for disaster.
One of the most asked questions I get when somebody is asking about my greenhouse is, "Do you heat it in the Winter"? Yes. They then proceed to ask how, how much heat is enough, what is a good source, etc, etc. These questions will depend on many things.
First, what kind of plants are you wanting to grow? You need to know the minimum temperature your "crop" can handle. The majority of things in my greenhouse can handle down into the mid 30's pretty much with no trouble. I am testing the limit this year with Theobroma cacao (chocolate), they don't like it below 40, but we will wait and see.
The next question would be: What is the greenhouse made of? My first year I had mine made out of 8 mil plastic. For those of you that are not sure what this is, think very heavy painters drop cloth, almost tarp like. It kept the heat in okay, nothing to write home about, but had to be replaced within two years. Plexiglass works very well, as does corrugated plastic and of course, glass.
Here, size does matter! If your greenhouse is 6 feet by 6 feet, you will not need as big a heater as you would if you had a greenhouse the size of a tractor trailer. Mine is 8 feet by 16 feet and I use a mid sized electric heater. Now remember, mine is not hermetically sealed, but in 18 degree weather in the middle of the night, I can maintain 33 degrees, cold, but not life threatening to the majority of plants.
Installing fans in your greenhouse is a good investment. Any kind will work, ceiling, box, oscillating, whatever you can afford and will fit. During the Winter when the greenhouse is heated, you need to maintain air circulation so that the temperatures remain uniform throughout. Without air-mixing fans, the warm air rises to the top and cool air settles around the lower part, where the plants are.
Watering can be very time consuming, especially if you have lots of plants. I almost have it down to a science. I drag the garden hose in there about once a week and just hose everything down. You need to be careful of any electrical cords, appliances(fans, heaters) or outlets you may have. As for the plants that don't need as much water as others, I put them where the taller, bigger plants block them. Higher shelves, corners, under over hanging shelves all work as water blockers. I have even stacked smaller plants on the soil of larger plants, the smaller ones need more and only after they have had enough, give some to the bigger ones.
A couple of other minor things to think about would be, Do I need additional lighting? Again, this will depend on the crop. If you are trying to grow Tomatoes, I would add more light. If you are just trying to keep something alive that may have lost it leaves or needs to go dormant, probably not.
Should I have a potting area? Only if you plan on spending lots of time and have lots of room in there. Again, mine is basically Winter storage for my plants. I do use some of the shelving in the Summer to repot or seed when I want to be out of the sun.
In the past, greenhouses were a luxury, today there are nearly 3 million hobby greenhouses in the U.S. and the number is expected to grow.
I hope this has sparked an interest in starting a greenhouse. Christmas is almost here and if you want to get a few hints out....cut out some pictures of greenhouses and leave them lying around. Send e-mails with greenhouse design websites to your significant other. If all else fails, send a letter to Santa! Whatever you do, get yourself a will be glad you did!
Happy Growing!

Sunday, December 5, 2010

Plant Cold Protection

I posted last week about bringing your houseplants in for the Winter. Hopefully you all did. What about the plants that are just way to big to move or are in the ground? Again, I am lucky in the aspect that I have a greenhouse and a fairly decent, healthy back, so I can move my 30 gallon pots. What if you don't have either of the above and want to protect that plant that is marginal in your neck of the woods?
Lets see if I can give you a few ideas.
Although I live in the Southern part of the United States, Winter sometimes brings cold temperatures that can cause severe damage to many of our landscape plants. Early frosts in the Fall can cause damage on plants that are normally adapted to our area. Plants need adequate time to harden off (adjust to outdoor conditions) before freezing temperatures occur. A plant’s ability to withstand cold temperatures will depend on the plant species, but also on how low and how fast temperatures decrease. When temperatures gradually decrease, a plant can acclimate, or adjust itself, to withstand colder temperatures better. Sudden decreases in temperature cause more damage in Fall or early Winter than similar low temperatures well into Winter. New growth that has been stimulated by late Summer pruning or fertilization is very susceptible. Hopefully you weren't outside in the past month or two feeding your plants or giving them a haircut. If you weren't, then you are already ahead of the game.
Ideally, The best way to prevent cold injury to plants is to choose ones that tolerate the cold temperatures in your area. We all know though, that pushing the envelope is sometimes more exciting and offers a wider range of plants.
So, in addition to right plant selection, you want to put the plant in the right place. During the Winter, the coldest spots are often found on the North and Northwest part of the property and in low areas where cold air settles. The warmest spots are usually on the Southern part of the property. Placing plants under non-leaf dropping trees will add some protection, as will using a fence, building, wall or temporary shelter made of plastic. Placing plants near a sidewalk or street can even add a few degrees of protection. These things absorb the heat and give it back off at night. For container grown plants, their roots are more exposed because they are above ground. Push together container plants that are left outside and mulch or cover them to decrease heat loss from the sides of the containers. Wrap the base of the containers in plastic, burlap, or blankets to reduce heat loss. Remember also, that plants that grow close to the ground are usually protected by heat radiating from the soil. Plants that are tall and more open do not receive this radiating heat and are not protected from the cold.
Covering your plants helps protect them from frost as well as from extremely cold temperatures. Covers that reach the ground and do not come in contact with foliage form a layer of insulation from the cold temperature. To prevent foliage breakage, avoid having the covers (sheets, blankets, painters drop cloth, etc) touch the foliage. This can be accomplished by using tomato cages for smaller plants and lumber teepees for larger ones. Don't forget to weigh down the sides so a gust of wind will not blow it off. When extremely cold temperatures are predicted, place a light bulb (60 watts or higher) or other heat source (spotlight) under the cover to provide heat. You can also use some of the old Christmas lights that we all had as children, you know, the ones that would melt your toy if it came in contact with? Check the lights before relying on them, the newer ones do not produce any heat. Be very careful when using a bulb or other heat source, which can be a potential fire hazard. Do not let the bulb or heat source come in contact with the plant (Christmas lights being a kind of exception) or the cover. Remove the cover and provide ventilation during the day, the sun can very easily burn the plant or at the very least, the extra warmth could possibly cause the plant to break dormancy. This precaution is critical when using plastic covers.
Watering plants before a freeze can help protect them from cold injury. Soil that is well watered absorbs more heat and gives it back to the plants at night. I don't have this problem here, but, Cold weather can also cause the ground to freeze. When this occurs, water is unavailable to roots; plants continue to transpire (lose water from their leaves) and dry out. Watering the soil to thaw the ground makes water available to roots.
Mulch will act as an insulator, so it too can protect plants, especially from wide swings in temperature. Sometimes the cold temperature is not what damages the plant, it's the freeze/thaw cycle affecting the soil and causing it to "heave" the plant. The roots basically get thrown out of the soil and break contact with it. Something to keep in mind about mulch, this "insulation" works both ways. It can prevent the soil from drastic swings,and getting too cold, but it can also prevent it from warming up when the time comes. You may wish to rake it back away from the plants as it starts to warm up in Spring.
Now occasionally, Mother Nature actually provides the best blanket of protection in the form of a light snow. Up to two or three inches of snow not only insulates the ground around your plants, but it also provides a blanket of protection over the leaves. If you have a situation in your area (I don't, usually) that this could happen, you need to think way in advance.
This is a picture of some Wax Myrtles, before the wet, heavy snow, hit us in February of this year. They were about 10 feet tall prior. If the homeowner knew this was coming, if ANY of us had known this was coming, they would have been pruned back in the middle of the Summer. This event caused considerable damage. Of the limbs that broke, some were as big as six inches in diameter. This picture was taken too late to do anything about it. What should have been done, other than the preemptive pruning? Someone should have gone out there and lightly shaken as much of the snow off as they could. The plants are fine and rebounded, but the shape of them is not one of beauty, Mother Nature is definitely not a landscape designer.  
To sum this all up, healthy plants are more resistant to cold injury than plants that are weakened by disease, by insect damage, or by improper care. Plants that are being grown in their proper growing zone will do better than one that is 3 zones off. With an ounce of prevention, and a little work, you too will produce a plant that can wear a tag that states "I survived the Winter of 2010/2011".
Happy Growing!