Citrus greening disease threatens the entire citrus industry


I always look forward to this time of year when citrus supplies are plentiful. My favorite one has always been the tangelo, but that is changing. It’s not because I like them less, it’s because they are nowhere to be found.

The reason for this is the citrus greening disease, sometimes called huanglongbing disease or HLB. It’s caused by a bacterium spread by a tiny sucking insect called a psyllid. Bacterial diseases are difficult to control in plants.

Bacteria reproduce extremely fast, so host plants must be treated constantly. That’s impractical for large acreages. The bactericides and insecticides also must be systemic and enter the plant tissue to be effective. Chemicals also can’t be toxic to the consumer.

Tangelos are among the most susceptible of all citrus types. Grapefruit, key lime, and clementine are more resistant. If you have been surprised to not find tangelos in the store, there’s good reason.  There are none.

Perhaps you’ve noticed more mandarin oranges at grocery stores than in past years. Mandarin types like clementines are somewhat more tolerant to the disease, and in recent years more farmers have planted them.

Once a tree is infected with HLB, there is no cure. The fruit yields in Florida are a fraction of what they were in 2000. Fruit prices have been on the rise to compensate for decreasing yields and everyone has suffered.

Plant pathologists have been working hard for over a decade to develop citrus that is resistant to these bacteria. They’ve also initiated programs to hinder the psyllid insect that carries them.

So, what does citrus greening disease actually do, you ask? Trees infected with the bacteria produce fruit that stays green even after it is ripe. It’s also bitter and poorly shaped. Sugar can’t be transported properly inside the plant, so fruit quality is poor and energy to the entire plant is limited. Infected trees usually die within a few years.

A few decades ago, another bacterial disease called citrus canker ravaged Florida. It’s still a concern. Entire orchards were quarantined and destroyed under government supervision. Many farmers were ruined, but it was minor compared to the present citrus greening problem.

Trees infected with that disease had fruits that had unsightly surface blemishes. They still were acceptable for much of the juice market. Citrus greening is different. Fruit quality is unacceptable for any human consumption. Sugars won’t translocate to the fruit normally.

Controlling both these diseases involves reducing the amount of disease inoculum available. That means destroying infected trees. Backyard gardeners must comply too. If either of these diseases is detected on any tree in a commercial orchard, nursery or private residence it must be destroyed.

Until recently the disease was limited to Florida and Texas in the US. It has now spread to California. Their problem has been less severe, but I suspect part of the reason is that the climate is less ideal for vector and pathogen growth.

Florida’s climate is hot and humid, while citrus producing areas in California are hot but far less humid. Whatever the case, we’re facing several more years of reduced citrus quality and yield. That’s a shame.

 

Ted Manzer teaches agriculture at Northeastern High School.

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Rose rosette disease is good for some and bad for others


Everyone has heard the expression to be careful what you wish for. Sometimes a cure for one problem can cause another. Rose rosette disease is a prime example.

Years ago, multiflora rose was planted as natural fencing and for soil conservation in the eastern US. It was also used as a rootstock for ornamental roses. Over the years, multiflora rose became one of the thorniest problems for livestock farmers. It also lowered pasture land value.

When I lived in West Virginia, multiflora rose dominated pastures. Some were so infested that livestock productivity was a fraction of what it could have been. Deer liked to eat them, and these roses provided great cover for deer and rabbits. Most farmers wanted the roses gone and overused pesticides to do so.

The last few times I have driven around in rural West Virginia I have noticed far fewer pastures dominated by multiflora rose. I suspect the major reason might be rose rosette disease.

I remember back in the 80s many agronomists and livestock scientists I worked with were discussing how this disease was reducing rose populations in the Midwest. These guys were interested in pasture and livestock production. They didn’t have much concern about the influence of rose rosette disease on ornamental roses.

However, this disease can be spread on ornamental roses like ‘knock out’ types mechanically through contaminated grafts. It also can be spread from plant to plant through natural root grafts. Likely the most common way the disease spreads is through a tiny mite. This mite transmits a virus. That virus is the major culprit in the demise of the wild multiflora rose population.

Virus diseases cannot be chemically controlled like fungus diseases can. Scientists continue to develop chemicals that can deactivate or inhibit viruses. However, viruses, particularly plant viruses mutate rapidly to overcome this. Basically, chemical control is difficult.

Knock out and other types of landscape roses are becoming increasingly popular. Because of this, I suspect we might be dealing with rose rosette disease more in the future. Roses with rose rosette disease develop clusters of bright red shoots in the spring. We call these clusters witches’ broom. This abnormal growth is easy to spot.

Many virus diseases can be controlled by removing infected tissue back to healthy wood. This is not one of them. Entire plants must be removed from the area or an entire rose planting might be in danger.

Homeowners might wonder what their best course of action might be if they don’t have any signs of this disease yet. I would suggest eliminating any wild multiflora roses that might be nearby. Cutting down canes and treating the surface with concentrated glyphosate seems to be the best method.

The good news is that multiflora roses aren’t very common around here. I know where a few patches are, but in general, interaction between wild and cultivated roses is limited. Still, this disease is something to keep in mind, especially since most roses are grown in areas where wild roses are more common.

 

Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).

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Agaves can be dual purpose succulents


It’s nice to be able to go on vacation and not worry about houseplants or flower gardens. There are two ways to accomplish this. The first is to set up an automatic watering system. The second is to choose plants that use little water.

Xeriscaping is becoming increasingly popular. Indoor succulents are also a hot commodity. Aloe, jade plant and ghost plant (Graptopetalum) are consistent sellers in our interior market. Hens and chicks, Sedums, prickly pears and ice plant tend to be the mainstays for exterior use.

Many agave cultivars are adapted to our climate. Still others will thrive indoors if given plenty of light. Some prosper in both environments. Often, people call them century plants.

Some folks might be familiar with agave as the source of tequila. The only agave I know of that is commercially used for tequila is the blue agave, and it isn’t hardy here. Agave syrup can be found in specialty stores, but it’s not a common sweetener used around here.

Agave plants basically have no stem until they bloom. Then, some varieties might shoot out a flower stalk more than 30 feet tall. Plants often don’t flower until they are decades old, hence the name century plant. Many folks have seen different agaves but didn’t know what they were.

Thick succulent leaves emerge to form a basal rosette. These plants may be variegated or any solid color ranging from green to grayish pink to blue. They look a little like Aloe vera or thick-leaved yucca plants.

Most agave are hardy to zone 9. Many are hardy to zone 7. My experience is that wet soils are a greater deterrent to survival than pure temperature. Last winter all my agave plants in pots survived, while my two planted in the ground perished. It was a wet winter as well as a cold one.

These succulents are great in decorative clay pots, and they perform well in raised sand mounded rock gardens. Their texture is conversational. In addition, many color patterns are available for this area. The best thing about them is that they require little care.

A problem could be that they don’t mix well with perennials typically used in our region. Too much water can be a major problem. Excellent soil drainage is a must.

On the culinary side, roasted agave hearts, leaves and stalks can often be found in authentic Mexican food stores, particularly in the southwest. They are frequently on the menu in restaurants there too.

Medicinally, agave has been used to treat many ailments. Constipation, jaundice, dysentery, scalp infections, and toothaches are just a few of the maladies that herbalists treat with agave. Sap and other preparations from both the roots and leaves can be used internally and topically.

Agave has anti-inflammatory and antiseptic properties. Hence it is often used to heal wounds, burns, and skin irritations. Native Americans in the southwestern states and in Mexico used agave root preparations to treat snakebites.

Agave sap can be a skin irritant to some people, much like that from mangoes. Most folks aren’t affected and there don’t appear to be any drug interaction problems with agave.

This one survived last winter quite nicely in an above ground container

This oe planted in the ground didn’t fare so well.

 

They make great house plants too

Ted Manzer teaches agriculture at Northeastern High School.

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Food lover’s holiday


There’s no holiday that stimulates the palate quite like Thanksgiving. Oh, I know food shouldn’t be our reason for looking forward to it. Despite the problems our citizens face we still have plenty to be thankful for, and I hope we never forget why we celebrate the holiday. It’s more than a time to stuff ourselves.

That said, it’s hard not to look forward to the food. It seems each region of the country has its own traditional staples. Turkey generally finds its way into most homes regardless of the locale, but the way we prepare it might vary a little.

Since deep fried turkey is largely cooked outside it stands to reason it is more popular in warmer regions. Louisiana and Kentucky were the first states to document the technique about 80 years ago. In California, grilled turkey is quite popular, and that tradition is spreading. It’s pretty common around here.

Collards are a major tradition in the south. It seems you can find them anywhere this time of year, but I never ate them growing up in Maine. We never had sweet potato biscuits or pecan pie either. Boiled onions and turnips were always on the table. I like both vegetables, but I never cared for either cooked that way. Raw or grilled suit my palate much better. We always had plenty of sweet apple cider, which I do relish.

Stuffed lobster is a Maine tradition, but it was too pricy for our Thanksgiving meal. Besides, we didn’t live on the coast where it was more prevalent and part of local culture. Mussels are popular holiday fare in many northern coastal places too.

For dessert, pumpkin and sweet potato pies are interchangeable. In fact, many can’t tell the difference, but pumpkin is more popular further north. We could grow pumpkins in Maine, but the season was too short for sweet potatoes. Whether used as a dessert, casserole or vegetable, sweet potatoes are as common on a southern Thanksgiving table as winter squash is on a New England one.

When I lived in West Virginia, mincemeat was a popular Thanksgiving treat. Pies were the usual use, but my mother-in-law made great mincemeat cookies. They were always loaded with freshly collected black walnuts and shagbark hickory nuts. Apple pie, green beans, deviled eggs, mashed potatoes and gravy always adorned her table too.

Stuffing seems to be a staple everywhere, but cornbread stuffing seems to be more popular here than wheat bread or rice-based types. Blue cornbread stuffing is popular in southwestern places. It’s usually spiced a little hotter too. We always stuffed our bird when I was young, but that is frowned upon now. The flavor and moistness were tough to beat though, and it’s funny how we never got sick. Maybe we had better immune systems back in the day.

In Texas and other border states Mexican-style cooking abounds. They sport a different pumpkin dish on the Thanksgiving table. Pumpkin empanadas are miniature pumpkin pie-like tarts. Corn pudding is a Midwestern tradition. When in Hawaii expect Thanksgiving dishes spiced with coconut, papaya, pineapple, macadamia nuts and other local staples. You might even find recipes incorporating spam.

 

Ted Manzer teaches agriculture at Northeastern High School.

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Cranberries can be an all season treat


Most people only eat cranberries at Thanksgiving or maybe Christmas. When they do find their way to our plates they’re usually smothered with sugar. If people only knew the benefits of this tart fruit they might try eating them more often and more naturally.

Cranberries (Vaccinium macrocarpon) are native to much of the Northeastern part of North America. Sunny places with moist sandy acidic soil are necessary for them to thrive. Growth requirements are quite specific. Soil pH should be no higher than 5.0, which is far too acid for most plants. Additionally, plants are shallow rooted and not drought tolerant, so water must always be abundant. Wild ones can be found in isolated areas in our area and in the mountains of western North Carolina but we are at the southern edge of their range.

Plants are very low growing. Often mature plants are less than two feet tall, so they can be easily shaded by taller and more aggressive species. Tiny oblong leaves emerge singly on creeping stems. Most branches creep along the ground but the ones that produce fruit are upright.

These delicate wiry vines produce their bounty in late fall. Cranberry season generally lasts from October until December. Each berry contains four seeds. Fruits are very acidic in taste, having a pH in the range of 2.3 to 2.5. Throughout the summer the developing cranberries are white, and they stay that way for a long time. White fruits should generally be avoided. Many people who see unripe cranberries think they are poisonous.

When these berries ripen they are not only edible, but they are among the healthiest fruits you can find. Only blueberries have higher levels of antioxidants. Interestingly, both belong to the same family. Cranberries are rich in vitamin C, E, K and fiber. They only contain about 50 calories in a one cup serving. That assumes you eat them raw without sugar, something many find hard to do.

These bright red fruits have strong antibacterial properties and are helpful for treating urinary tract infections. Part of the reason is that they turn urine acidic and bacteria generally struggle in acidic environments.  Acidity also helps prevent formation of alkaline calcium ammonium phosphate stones in the urinary tract.

Cranberries do contain significant levels of oxalates, which could contribute to Calcium oxalate stones, however. Not all kidney stones are the same. High levels of vitamin K also could be a problem for people on blood thinning medicines.

Cranberries can keep in the refrigerator for up to two months. They also freeze well. While I’ve raved about their fresh use, they are also a great addition to your favorite apple pie recipe. Add cooked cranberries to your apple sauce too. They add flavor and color. They’re super in salads too, fresh or dried.

These red morsels should be part of our diet all year, not just at Thanksgiving and Christmas, though that is when they are most plentiful. Learn to appreciate their tart flavor and give these powerful disease fighting vitamin packed fruits a spot on your table all year.

small bunch of cranberries all cleaned up and ready for use

Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).

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Catnip and catmint are confusing cousins


To most folks they are interchangeable. Catnip and catmint are closely related perennial herbs in the mint family. If I had to state their greatest deference it would be that catmint has more ornamental value. Catnip is more of a medicinal herb.

Catnip (Nepeta cataria) and catmint (other Nepeta species distinctly different from N. cararia) both thrive in full sun and both can tolerate significant drought once established. Neither tolerates acid soil particularly well, and both prefer well-drained conditions. In our area, long periods of hot humid days can be problematic.

Catmint varieties normally grow 12-18 inches tall, while catnip might reach heights of more than four feet. Catnip also tolerates shade better. Both are very winter hardy.

These mints have tooth edged leaves that emerge in groups of two. Stems are square, and both have sprawling growth habits. Both are easily propagated by seed or stem cuttings. Seeds are very small and produced in large numbers.

Catmint also blooms more profusely. During summer it can be a sea of purple. Catnip has far more foliage, is more stemmy and sports short spikes of lavender flowers.

These herbs attract hummingbirds, bees and other pollinators. Deer avoid them. In fact, some people plant catnip and catmint simply to repel deer. However, in areas with dense cat populations it’s sometimes difficult to get these perennial herbs established. Cats will roll in them and root them out.

These pungent herbs belong to the genus Nepeta and contain the compound nepetalactone. This is what drives cats crazy. The chemical is somewhat stronger in catnip than catmint.

Though people have told me differently, from everything I’ve read, no corroborating evidence exists that catnip has lasting long-term effects on cats. However, nepetalactone will alter their personality in the short term. Many cats aren’t affected that way, and some show no interest in it at all.

Some research claims catnip and catmint to be effective insect repellants. However, their effectiveness is short-lived. Constant re-applications are necessary. I’ve heard these herbs can be planted around barns to keep rats and mice away. I suspect that’s mostly because the plants would draw cats.

As far as humans go, both these herbs are commonly used. Catmint makes a relaxing herbal tea. Most folks might want to sweeten it. Both mints are used in cooking, but flavor can be overpowering in large amounts.

Leaves can also be eaten raw in salads. It’s my opinion that the smell of catnip is better than the taste. In concentrated doses it can be used to promote vomiting. If that doesn’t sound appetizing, sometimes catnip preparations are applied directly to the skin to relieve pain.

Both catnip and catmint are used as diuretics. They increase urine flow. Lithium is used to treat bipolar disorder, depression, schizophrenia and some eating disorders.  Catmint or catnip use can interact and limit how the body rids itself of excess lithium. That’s not good.

Catnip is often used as a sedative to cause drowsiness. This could pose a problem for people already taking medication for this. It’s always critical to consult your medical professional before embarking on any new herbal medication regimen.

 

Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).

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Dianthus provide a wide variety of great cool-season flowers


When folks ask about dianthus I smile. It’s like asking a kid if he likes candy bars. The obvious answer is yes, but there are so many different kinds to choose from.

Dianthus is a genus with a great variety of members. Their common name is ‘pink’, but many are not that color. All pinks have flowers with ragged edges, almost like their petals have been attacked by pinking shears.

Dianthus are carnation relatives. In our area, most are perennial, but many types are marketed as annuals. Numerous varieties are even winter hardy when planted in containers in eastern North Carolina.

Some types have solitary flowers, usually a couple inches or more across and can be from six inches to over two feet tall. These are what we generally call carnations (Dianthus caryophyllus).

. They can be grown in perennial gardens and are often used as cut flowers. Carnations have been cultivated for many centuries and are a florist industry staple.

Some true carnations have much smaller flowers, so we call them dianthus and not carnations. We usually reserve the carnation name for the large flowered types, whether they are tall or not.

A second old time type is called Sweet William (Dianthus barbatus). These are popular because they are easily established from seed. Sweet Williams are true biennials, but we usually treat them as perennials, because they re-seed themselves so freely.

A biennial is a plant that completes its life-cycle in two years. They produce a strong root system with plenty of stored energy in their first year, and they flower and go to seed in the second. Copious amounts of seed mean many new plants and the appearance of being perennial.

Cheddar pinks (Dianthus grataniapolitensis) and maiden pinks (Dianthus deltoides) are two other perennial types commonly used in gardens. Maiden pinks provide a delicate texture and pleasant fragrance. Cheddar pinks bestow a mass of color to a planting. Most varieties are pink.

Cheddar pinks are often used as ground covers and they form dense patches. In our summer heat they usually struggle unless soils are sandy, or they are planted in raised beds.

Another type of pink is annual dianthus (Dianthus chinensis). This is somewhat of a

misnomer, as in northeastern North Carolina most are perennial. Some cultivars don’t persist more than a few years, but they still come back in the spring. This type usually flowers heavily.

In our locale, all dianthus species thrive and flower more heavily in cooler weather. They also perform better in sunny well-drained soils. I think that’s why they do so well in large pots with coarse artificial mix.

Dianthus flowers are also edible and are sometimes used to decorate salads. They make a delicate flavored tea too. The upper portion of the petals have sweet pleasant taste. Petal bases can be bitter. Years ago, dianthus species were widely used medicinally. They aren’t anymore.

When I was a kid I remember farm animals trying to steal Captain Kangaroo’s carnation. I assumed that meant plants were palatable, but deer and other animals usually leave them alone. I guess I can’t rely on memories from 55 plus years ago.

Dianthus showing the tooth-edged petals

Marketed as annual dianthus, it is perennial in eastern North Carolina.

 

Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).

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