Wildflowers: Ruellia humilis

Right now, untended fields are full of blooming Ruellia humilis, or Wild Petunia.  This is the untamed cousin of the 'Katie' ruellia you see in the nursery.  It blooms from May through about October, and is variable in color:  blooms can range from almost white to very dark indigo.  Ruellia is perennial, and tough as nails -- you already know this if you've tried to remove it from a flowerbed once it's established.  Ruellia humilis grows to about 2 feet tall and will do well in sun, part sun, and bright shade.  It isn't really picky about soil conditions, either.  Ruellia is a forage plant for browsing animals and attracts butterflies and moths.  Ruellia can be very assertive, though:  plant it in a place where you know you'll always want it!

Foliage Friday: Gumpo Azalea

I know.  Usually azalea is a flower plant.  But I love this little Gumpo azalea for its foliage and its form.  It's neat and mounded, with tiny leaves, like a rounded, decorated boxwood.  Though it's slow-growing, it's tidy and dense.  This one is not quite as hardy as other varieties; perhaps only suitable for zone 7b and south.

Pink Gumpo Azalea, in August.

The Gumpo azaleas are part of the Satsuki group, first codified by the Japanese in 1692.  'Satsuki' means 'fifth month' and these azaleas bloom in the fifth month of the old lunar calendar, our equivalent of June.  They are available with white, pink and red flowers.  There's even a "Fancy" variety that is pink with a white margin.  Because they bloom later than the Southern Indicas, the flowers are somewhat hidden by the spring flush of foliage.  The color display isn't nearly as dramatic as the March extravaganza of the spring-blooming varieties.  Gumpo azaleas have a shy appearance, a little more standoffish. 

'Kinpo,' a Satsuki azalea.  Photo: Jim Trumbly

And here's one more reason I love Gumpo azaleas.  They aren't Encore™ azaleas.  I don't have anything against Encore™ azaleas.  But I miss the old varieties.  Houston is azalea country -- and those so-called "repeat bloomers" are crowding out my old favorites, like the Kurumes, the Pericats, the Glenn Dales, and the enormous number of Southern Indica hybrids.  Here's two more, just so we don't forget...

'Hinodegiri,' a Kurume azalea.  Photo: Joe Coleman

'Mary Margaret,' a Glenn Dale azalea.  Photo: Dan Krabill

Grafting. OMG!

One of our activities in the citriculture class last week was grafting.  My heart sank.

Grafting Knife.  Scary.

I don't like grafting.  I don't like the fiddly tools.  I can't see well enough to make a clean cut.  I get nervous in a room full of people with sharp knives and paraffin tape.  However, sometimes I can manage to rise to the occasion.

Rootstock.  Skinny.

My mission:  graft Everhard Navel Orange budwood to Poncirus trifoliata (Flying Dragon) rootstock.  We used a T-Budding technique, that involved both a vertical and a horizontal cut in the rootstock.  (Egads!)  Once those cuts were complete, we slid a slice of budwood up underneath the flaps of rootstock bark.  It's harder than it sounds.

Vertical Cut.  Gina's Steady Hands.

The rootstock was tiny and so were the buds.  I have no hope that it will work, but the graft is still green, not black, so I'm not giving up.  We're supposed to leave the graft alone for about 3 weeks.  If it works, the budwood should emerge right through the Buddy Tape.  We'll see about that!

Horizontal Cut.  Almost done!

If you make the vertical and horizontal cuts correctly, you'll form an upside-down T.  The wings of bark will curl up a little tiny bit, offering a spot to slide the budwood in, up underneath the loose or "slipping" bark.  Also, easier said than done.

Wrapping with Buddy Tape.  Needs 3 hands.

The Buddy Tape is waterproof, yet permeable.  Biodegradable yet strong enough to protect the wounded rootstock.  It can also be stretched up to 8 times its original length.  Sounds like witchcraft, doesn't it?

Complete.  At last!

And here it is, the completed little graft.  It will truly be a miracle if this works.  I'll let you know.

Wordless Wednesday

Catfacing on Pears

Pears in Texas are commonly harvested in August, and it looks like it's been a good year, for the most part.  The winter weather we had ensured that most of our trees got enough chill hours to flower well, and we haven't had to endure the droughts of last year.  I've seen some great looking pears, but also some with catfacing.

Catfacing Damage on Pears

What causes this kind of fruit deformation?  Sucking insects, such as leaffooted bugs, boxelder bugs, stink bugs and lygus bugs.  These insects feed on the surface of the developing fruit, killing cells.  As the fruit matures, it dimples into what someone must have thought looked like a cat's face.  By the time you see this level of damage, it's too late to treat the cause.  Most of these insects migrate in from nearby fields or fly up from debris on the orchard floor.  Normally, this is only a sporadic problem.  You may not have it every year or you may only have the problem on a few of your trees.  Monitor closely early and late in the season, during pre-bloom through early fruit development and again in late summer or early fall.  Look for the adults and nymphs who are feeding on developing or mature fruit. 

 (Leaffooted Plant Bug, Adult and Nymph)

To control them, watch for groundcovers that harbor overwintering adults.  Limit overuse of insecticidal sprays (organic or conventional) that may harm natural predators.  As a last resort, use an insecticidal spray in the spring just as adults emerge from hibernation, usually around petal-fall.  Don't apply unless the problem is severe: these insects rapidly build up resistance and the sprays do harm natural predators.  For that reason, spot treatment is better than spraying everything in sight.  Don't spray during bloom: all listed products are toxic to pollinators. 

One of several Lygus bug species.  Photo by Scott Bauer, USDA

Citrus Greening and Asian Citrus Psyllids

Last week, I attended a specialist training class on citriculture, with a special emphasis on Citrus Greening (CG) and Asian Citrus Psyllids (ACP).  Citrus Greening is an incurable bacterial disease that affects all kinds of citrus and related plants.  It is spread by the Asian Citrus Psyllid, a small insect that transmits the disease while feeding on the sap of the host plant.

Asian Citrus Psyllid, Photo: David Hall, USDA

CG is a devastating disease that originated in the Far East but is now spreading throughout the New World.  The disease is currently present in Florida, Louisiana, South Carolina and Georgia, as well Belize, Cuba, Jamaica and parts of Mexico.  The psyllids that transmit the disease are present in these states, as well as Alabama, Arizona, California, Guam, Hawaii, Mississippi, Puerto Rico, Texas and the Virgin Islands.   It is likely that hurricanes play a role in spreading the disease by translocating infected insects.

Symptoms of Citrus Greening, Photo by J.M. Bové, bugwood.org)

We can't do much about hurricanes but we can help prevent the spread of Citrus Greening and the migration of Asian Citrus Psyllids.  All areas where either the disease or the insect have been found are under quarantine.  It's against the law to move citrus or other related plants from an area with either CG or ACP to another area.  Please don't move citrus plants, leaves or fruit into or out of a quarantine area.  If you purchase citrus, make sure you are dealing with a reputable supplier who understands and complies with federal and state regulations.  This disease has the potential to eradicate the entire citrus industry in Texas. 

As part of my training, I'll be inspecting citrus trees around here, looking for signs of the disease or the psyllids themselves.  I hope I don't find them!  For more information about citrus greening, see the websites listed below.  Check back frequently as the situation changes rapidly.

USDA APHIS Plant Health

Florida Department of Agriculture Citrus Health Response Program

California Citrus Research Board

LSU Ag Center Asian Citrus Psyllid and Greening Disease

Clemson University Citrus Greening

Texas Department of Agriculture Citrus Greening

Stop Girdling Those Trees!

I know you don't mean to.  Maybe you don't even realize what you're doing, if you have a lawn crew.  But some of you out there are condemning your trees to a slow, awful death.  The tree spirits will haunt you for this, I promise.

Using a string trimmer right up against a tree is a serious no-no.  Once the cambium layer is severed all the way around a tree, the flow of sap is interrupted and the tree will die without fail.  The cambium layer is between the old, hard wood (the inner core of the tree) and the bark.  It is the living tissue of the tree, the most important part.  If you scrape your fingernail along a woody stem, the cambium is the green skin you see.  It's responsible for growth and healing and without an intact system, your tree is lost.

In fact, cutting all the way around the trunk of a tree, or girdling, is an ancient land-clearing method.  In most cases, it will kill a tree in one growing season.  In between mowings and trimmings, your tree is going to try to repair damage to its trunk, but over time, the string trimmer will win.  The tree below, in the common area of our neighborhood, was killed by girdling and is now marked with paint for removal.

I see some of you are trying to protect your young trees with collars like these, which I guess is, at least temporarily, better than being whipped to death by a string trimmer.  But please don't forget to remove the collar.  If the tree grows over it, the collar will girdle the tree as surely as cutting the cambium will.

A better idea?  Clear the grass from around the trunk, all the way out to the dripline, if possible.  This will keep the lawnmowers and string trimmers away from the trunk, and reduce competition for water.  Cover the bare soil with a light layer of mulch, not a volcano.  You should still be able to see the flare where the trunk meets the ground. 

By the way, trunk damage is even more serious in palm trees.  Palm trees are anatomically more like grasses than hardwood trees, and cannot heal damage to the trunks.