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Horse fly can be any member of the insect family Tabanidae (order Diptera), but specifically members of the genus Tabanus, which are biting flies, a legendary nuisance to livestock, pets, and humans.
Since May this year, we are experiencing high horse fly infestations across regions, because of the frequent rain and humidity in Alabama. I have called for horse images and specimens for identification and to enable recommendations for control. A sincere Thank You to all (extension agents and clients) who responded in actions.
Review of all the images and specimens indicate we are dealing with one species: Tabanus trimaculatus. This identification has been confirmed by the livestock fly expert, Dr. Dan Kline, at USDA/ARS.
Horse flies are woodland dweller, enjoy moist areas and habitats. They deposit egg masses on vegetation in or near water where the larvae can burrow into moist soil. The larvae are cannibolists, eat organic matter and small arthropods and replies.
Horse fly picture taken by Patty Tyler (right).
Males don't bite, but live on plant nectar and pollen.These large, stout-bodied female flies are powerful and agile flies, circling or chasing their targets with deadening persistence to deliver painful jabs to the skin and to suck blood. The flies only stay in contact with a host for a few minutes to get the blood-meal and then they are gone until they need to eat again which is every 3-4 days. Beyond blood-feeding, horse flies, on rare occasions, carry diseases pathogens to livestock and horses.
Often, horse flies are far too mobile and numerous to control with insecticides: topical pesticides is ineffective due to horse fly behavior, but short term control is possible. Aerial applications and treating for the larvae are ineffective. Repellents don't work well either. Thus it is not an easy job to achieve horse fly control. So what is an Alabama to do?
Reducing the amount of standing water on your property will help keep horse fly populations low, though this is easy said than done. If the fly problem is in stall, get manure out of the stall quickly, deposit far away from the barn, and clean all wet areas. The manure needs to be dragged to distribute in a THIN layer over a wide area, so to let it dry out quickly. Fly larva cannot develop in dry environment.
Avoidance of tabanids is often the best strategy. Don't confine pets to tabanid-infested areas, and move them indoors if possible.
For humans, horse flies can be gratifyingly inept. They are not very sneaky, having extremely noisy flight, and they can be slow to bite after landing on the skin. Horse flies are therefore vulnerable to a well-targeted slap or swap.
But this may not be an easy job to protecting animals from being attached. The best option is to provide shelter for the animals or pasturing them away from infested areas. Another option is feeding animals with a supplement containing IGR. It is better start this in later Match until fall.
Traps have been proven to be practically well in providing effective control.
If the issue is in residential area: Using traps to reduce fly population. Traps can be box traps, sticky traps, and light traps. Female flies are attracted to carbon dioxide, light, and moving dark objects).
Traps specifically designed for capturing horse flies are H-traps, box traps, and Nzi traps. Mosquito Magnet Independence CO2 baited trap also work well in capturing horse flies, but it is expensive. None claim to conquer them all but you can kill many. These commercial traps utilize horse fly behaviors to lure flies with CO2, dry ice, or dangling black ball coated with Tanglefoot.
Tabanid traps can be bought or home-built using the same general idea. You can hang black balls/spheres where the flies frequented, trap flies in an inverted galss jar or coat the black balls with Tanglefoot (a sticky petroleum product available at hardware stores). Since tabanids are attracted by carbon dioxide, it might be interesting to try adding dry ice to your trap design.
Fortunately for us, tabanid numbers tend to outburst suddenly, and then go away within a short period of time.
Home-made ball coated with Tangelfoot. Photo from Dr. Dan Kline, USDA/ARS.
Xing Ping Hu
Department of Entomology and Plant Pathology
(Mallory Kelley, Home Grounds REA)
Scouting and monitoring your garden for pests at least two to three times per week can greatly reduce the damage that is acquired from insects. It is also very helpful to use a 10X hand lens to help identify small insects and insect eggs. Keeping records will help identify their peak activity each season and can help you predict when peak activity might occur in future years. If you have a field of tomatoes, sample the field in a pattern that covers the entire field in a zigzag pattern. It is best to check plants along the field edges separately. Then walk into the field to begin the zigzag pattern.
The most common caterpillar (aka, worm) pests of tomatoes include fruitworms, armyworms and hornworms. Other insect pests include aphids, whiteflies, leaf-footed bugs and stink bugs. Tomato fruitworms, armyworms and hornworms may be controlled by sprays of Bacillus thuringiensis (Dipel, Thuricide, along with others). This naturally occuring bacteria only kills caterpillars. Always read the labels to know what insects a pesticide will control, and if it is safe for vegetables. The most effective control time is just after eggs hatch and caterpillars are still small. Insecticidal soaps are effective for control of aphids and whiteflies if sprays are directed to the upper and lower leaf surfaces. Insecticidal soaps only kill stinkbugs when newly hatched.
From my own personal experience, caterpillars (aka, worms) on your newly set tomatoes can be very depressing. Just as we're ready to eat these on a sandwich…so are the worms. Below are the worms most commonly found in your garden on your tomatoes. Refer to these pictures when you scout and use the appropriate control measures to ensure that you get to reap your own tomato harvest. Tomato Fruitworms or bollworms, feeds on more than 100 plants including the tomato, but prefers corn. Newly hatched larvae usually enter tomato fruit at the stem end when the fruit is small and green. They bore deeply into the fruit and during development they may emerge from one fruit and enter another. Their feeding results in a watery, internal cavity filled with feces; damaged fruit will ripen prematurely and be susceptible to secondary invasion by fungi and bacteria.
Beet armyworm is primarily a foliage feeder, but they will also attack fruit, usually creating single or closely grouped round or irregularly shaped holes. Feeding damage is usually superficial, and larvae only occasionally develop inside the fruit. Unfortunately, other organisms can then enter the feeding-damaged areas and can rot the fruit.
Yellowstriped armyworms feeds on a variety of crops including tomatoes, alfalfa, bean, beet, cabbage, clover, corn, cotton, cucumber, grape, grass, morning glory, onion, pea, peach, peanut, sweet potato, tobacco, turnip, wheat, and watermelon. The insect usually overwinters as a pupa in the soil. Egg masses are deposited on foliage, trees, or buildings. There are three to five generations per year. Yellowstriped armyworms feed during the day.
Depending on the year, environmental conditions, and proximity of adjacent host crops, infestations of these insects on tomatoes may range from very light to extremely severe. The tomato fruitworm (aka, corn earworm and bollworm), and the beet armyworm both overwinter in Alabama; so early season infestations of these species may occur. However, later season tomato plantings are often damaged more severely because fruitworm and armyworm populations generally increase as the season progresses. It is common that the most severe fruitworm damage in tomatoes occurs after dry-down or harvest of adjacent corn, and heavy beet armyworm damage in tomatoes occurs after population buildup on cotton. An effective strategy for managing the fruitworm and armyworm is to monitor fields regularly for signs of insects or damage and to apply an insecticide only when necessary.
Field trials in Alabama tomatoes demonstrated that using insecticides in conjunction with a monitoring program saved an average of $44 to $65 per acre in insecticide costs alone; when compared with a program applying insecticides on a weekly basis. In addition to applying insecticides only when needed, the fruitworm/armyworm scouting program enables growers to apply sprays at the optimal time, when the worms are young and most susceptible to insecticides.
Sampling for Tomato Fruitworm and Armyworms Because beet armyworm is a foliage feeder, infestations may begin early--before the flower and fruit stage. Therefore, it is prudent to check young plants regularly for beet armyworm egg masses or small larvae. The presence of beet armyworm larvae can also be detected by shaking foliage over a shake cloth. The critical period for tomato fruitworm and fruitworm egg sampling begins at flower or, at the latest, when there are a significant number of green fruit at least 1 inch in diameter. Fruitworms are usually not a concern before flowering unless high numbers are present. Beet armyworm egg masses are covered by fuzzy white scales and are easy to spot. It is a good idea to check or shake some of the lower foliage for beet armyworm egg masses and larvae.
Fruit sampling serves as an extra precaution and a backup to the foliage sampling for worms and worm eggs. When scouting for insects and insect damage, check out the fruit. Tomatoes at least 1 inch in diameter are good candidates of insect attractants and damage. Check to see if any fruit have worm-feeding damage. Slice open damaged fruit to determine if damage is due to fruitworm (feeding deep inside fruit, feces often present) or armyworm (feeding usually confined to the surface). It is important to know which worm species is present to select the most effective insecticide needed.
Tomato hornworm Hornwormlarvae usually have green bodies with seven diagonal white stripes on the side, or eight V-shaped markings, depending on the species. The name comes from the large horn on the posterior end of the body. Hornworms can grow longer than 4-1/2 inches in length. They strip the leaves and may cause feeding scars on fruit. Hornworms are often controlled naturally by parasites. Parasitized hornworms may be identified by the presence of many white cocoons attached to the upper body surface. The preferred management approach is to wait until fruit begins to mature before applying insecticides. Insecticides may be applied sooner if extensive foliar feeding is observed. Insecticides are not highly effective against late stage larvae.
Our wet and humid summer may not have been the best for your garden, but these conditions have been quite hospitable for plant fungal and disease issues. Even as we begin to dry out and get a break from the constant rain, we are still seeing signs left behind in the garden from our saturated summer. One seemingly alarming problem that might pop up in your lawn is slime mold. While this is usually a widespread issue in late spring and early summer in Alabama, it can be seen sporadically throughout the year, and has recently been spotted in Mobile County. Slime mold slowly spreads up onto the turfgrass leaves when wet conditions persist. At this stage, slime mold might look like oil or dog vomit, depending on which type you have. Once on the grass, the slime mold produces spores that dry up into a gray or white crust, making for easy spore dispersal. Sounds spooky, but slime molds are not harmful to plants, us or our pets. Be sure you have good drainage throughout your lawn area and keep thatch build-up to a minimum (mow once or twice per week in growing season) as slime mold feeds on decaying organic matter. Slime mold can easily be taken care of by hosing off your lawn or through mowing or light raking when it has already formed the crusty fruiting bodies. Or, you can embrace your slime mold and work it into your Halloween decorations… it can be pretty scary-looking!
Photo: Crusty gray fruiting bodies of slime mold seen on turf in Mobile County.
Q. My peach trees struggled this year. The fruit set was very sparse, and the fruit that did make was inedible due to disease and bug holes. Can you provide some tips to hopefully prevent a repeat of last year?Photo credit – Chris Becker, Alabama Extension
A. I am so glad that you asked this question now. For some folks, their peach trees are the last thing on their minds in fall and winter. However, there are some steps that you can take now to help alleviate a lot of problems when spring does roll around. Also, now is a great time to develop an annual maintenance plan to make sure that each season is a “fruitful” one.
Right now, you should be thinking about steps to controlling insects and disease. If any fruit fell to ground this year, pick it up and dispose of it. Diseases can over-winter on fallen fruits. Fungal diseases are prevalent in our climate so it’s difficult, even with cleanliness, to grow peaches in Alabama without a spray program. More backyard fruit trees die from pests that could have been prevented with dormant sprays than from any other cause. In mid to late winter, you should make your first “dormant oil” application, making sure that the air temperature is above freezing. Three weeks later, you should make a repeat dormant oil application. As winter moves into spring, peach trees should be sprayed with a fungicide (like copper or chlorothalonil), just prior to flowering. This step should be repeated every 2 weeks until harvest. Additionally, an insecticide should be applied in 2-week intervals AFTER the blooms fall from the trees. This prevents peach curculio, fruit moth, and others. These applications should occur until harvest, as well. Timing of the insecticide application is crucial so that beneficial pollinators are protected.
Another important step in proper peach maintenance is correct pruning. Peaches should be trained to the open-center system. A properly pruned peach tree will have an upside-down umbrella shape. Remove any diseased or broken branches as well as all vigorous shoots growing upward or crossing over the middle of the canopy of the tree. Now, you know how to prune, but what about timing? Peach trees should always be pruned in mid- to late February, after the threat of freezing weather has passed. This process should take place just before trees leaf out. Pruning too early in the season encourages bacterial canker and could lead to tree death.
Adequate fertilization is essential to peach tree success. In early March, you should apply a cup of 10-10-10 (or similar analysis) fertilizer per year of tree age. Do not exceed a maximum of 10 cups for mature trees. In August, after all fruit is harvested, apply a cup of calcium nitrate per year of tree age, not exceeding 4 cups for mature trees.
One other tip is directly related to fruit size. The greater the number of peaches on the tree, the smaller those peaches will be. To prevent limb breakage and ensure fruit quality, you should thin peaches about four weeks after full bloom, or just after the natural “May” fruit drop. Hand-thin peaches, leaving about 6” between the remaining fruit on the tree.
I hope these tips are helpful. Yes, I know that it might be a little early to talk about peaches, but developing a maintenance plan now is essential to ensuring a bountiful harvest later. Happy gardening!
Written by Bethany A. O’Rear of the Alabama Cooperative Extension System (ACES).
"The History of Corn" probably sounds like a topic too esoteric to be anything but a good sleep aid. The history of corn is in fact an interesting and inspiring one. Corn as we know it today is not a product of the natural world, but rather the culmination of thousands of years of human ingenuity and applied horticultural knowledge. Generation upon generation of selective breeding has produced one of the most important food crops on Earth, with more corn produced worldwide every year than any other cereal product and corn being the number one agricultural product produced in the United States. This global super crop can trace its humble begginings back to central Mexico, where it originated from a diminutive grass called teosinte. [photo credit: John Doebley, https://teosinte.wisc.edu/images.html]
At first glance, teosinte appears about as different from modern corn as a wolf from a pomeranian. The most obvious difference is its branched growth, with each branch ending in a single female flower which produces a kernal. These may eventually develop into small ears, formed of a single stack of unfused kernals. Also unlike the ears of modern corn, those of teosinte are not husked and only about one inch in length. Before cultivation, these plants would typically produce just one "ear" at a time. It was around 10,000 years ago that early farmers began to notice that some plants produced more kernals than others, or that some kernals were tastier than others, and so they began to save and replant only the seeds of those plants with these decidedly superior fruiting habits. This selecting process continued over thousands of years, eventually resulting in plants which could produce multiple ears at a time, each several inches long and containing numerous large, fused kernals. These plants are what we know today as corn, or maize. Teosinte still exists in its native range to this day, but it is endangered and the number of individual plants is dwindling.
From Mexico, corn spread northward to what is presently the Southwestern United States, and southward to what is presently Peru. In North America, selective breeding (via cross-pollination) continued for many more generations to produce corn plants suitable for colder climates. These plants were bred to produce ears within a much shorter growing season. Eventually, by crossing and selecting plants that produced ears earlier in their growth, Native Americans developed corn plants which matured within three months after planting. By the time Europeans first made the voyage to North America and encountered its native residents, corn was already a major part of the native diet. You probably know the fabled story of the first Thanksgiving, but did you know corn was likely served as a porridge sweetened with molasses?
From the New World, corn was one of numerous crops traded between Native Americans and European settlers starting with Christopher Columbus. Today, corn is grown around the world and exists in a number of forms such as the sweet corn grown for human consumption, field corn grown for animal feed, and colorful flint corn (also known as Indian corn or ornamental corn), of which popcorn is a variant. Corn, so important to the diets of the Native Americans who first cultivated and developed it, is now ubiquitous to many cultures.
Aside from its food value, 40% of the corn produced in the United States is used to make corn ethanol. It is mainly used as an additive in gasoline, and some vehicles are capable of running on 100% ethanol. Corn is also used to make numerous industrial products including pharmaceuticals, fabrics, makeup, explosives, paper goods and paints.
The history of corn continues with genetically modified varieties which accounts for 85% of all corn planted in the United States as of 2009. These varieties are engineered to tolerate damage from herbicides, insect pests, diseases, and drought.
The story of corn is a significant piece in the story of humanity. When our ancestors were hunting and foraging in the harsh wilderness of several continents, corn's own ancestor was growing wild and free. Then came our shared journey into the world of agriculture leading to the rise of modern civilizations. Now, man and corn walk leaf-in-hand into the world of tomorrow. This holiday season, remember all that we and corn have been through together, all that corn has given us, and offer corn the respect it is due.
How much water do you use a day? Would you believe 60-80 gallons is an average amount of water used per person per day?
There are simple habits we can adopt to conserve our water use at all times, but especially in times of drought. Watching water use in our homes makes a difference in making a limited resource go further.
Inside the home water savings:
1. Take short showers instead of baths or only fill tub ½ full.
2. Install water saving toilets and showerheads.
3. Turn the water off when brushing teeth, shaving, washing dishes, and more.
4. Wash clothes and dishes only when you have a full load.
5. Waiting for the water to get warm? Catch that cool water for plant watering.
6. Check for leaky toilets and faucets that waste water.
Outdoor water savings:
1. Limit outdoor watering to the coolest part of the day. Consider using soaker hoses or trickle irrigation for trees and shrubs. Grass can go dormant in dry times and recover when normal rainfall patterns return.
2. Check irrigation systems for correct adjustment and leaks.
3. Group plants with similar water needs in the landscape and consider drought tolerant plants.
4. Mulch around shrubs and in flower beds to retain soil moisture.
Learn more ways to reduce your water usage here. You can also keep up with all the latest drrought information for both consumers and farmers at www.AlabamaDrought.com.
Timely Information pub:
2016 Water Conservation timely info.pdf
By Bethany A. O’Rear
Q. Autumn is my favorite time of year. The air is getting cooler, the holidays are just around the corner, and the leaves, even though this year’s drought has subdued the brilliant hues that we know and love, still put on a colorful show. However, all too soon, they flutter to the ground, bringing with them the annual question, “What can I do with all of these leaves?” Other than taking on the monumental task of raking and bagging, do you have any suggestions?
A. I love this time of year as well. I always look forward to fall’s brilliant display of color, but, as you mentioned, the drought has taken a toll on how vivid our fall appears this year. Additionally, it has also caused leaves to drop earlier and in greater numbers. Instead of sporadically falling over several weeks, many landscapes have seen a deluge of leaves hitting the ground all at one time.
Who among us didn’t grow up with the yearly task of raking and bagging leaves for disposal in the landfill? While it was hard work, the occasional dive into the leaf pile made it almost worth it, but, this method is not a good use of our natural resources. Other folks still rake and burn their leaves, which is not only a waste of valuable organic matter, but can also become a fire hazard, depending on the amount of rain that has fallen. This is especially true this year, due to the fact that 46 of our 67 counties are under a burn ban.
There are several other options for leaf disposal. A great way to make use of all of those leaves is to turn them into mulch, and the best method for accomplishing this is by using the lawn mower bagging attachment. The mower helps to shred the leaves, making them less bulky, and more easily handled. After shredding, you can spread leaves around the bases of trees and shrubs, or in your annual and perennial beds to cover any bare soil areas. The gradual decomposition of this leaf layer will result in the addition of valuable organic matter to your soil, as well as moisture conservation and reduced weed growth. One point to consider – leaves break down fairly quickly as a mulch layer. Consequently, you will need to add material a little more often than you would if using bark mulch. If you are like most of us, you have a bountiful supply, so that should be no problem!
Composting is another option for the disposal of all of those leaves. If you have a compost bin, fill it in the fall and keep any remaining leaves in a holding bin or in plastic bags stored nearby. As leaves settle in the bin, continue to add the remaining leaves. Leaves, in their natural form, are somewhat difficult to decompose. Shredding the leaves will be a tremendous help to the decomposition process. You can also speed up the process with the addition of microorganisms. By incorporating a few grass clippings, composted manure, or fertilizer into the compost bin, the leaves can be reduced to a rich organic amendment for your future gardening needs.
If you don’t have a compost bin, you can create a compost heap, which is simply a free-standing pile of leaves. A good, workable size for a compost heap is about 3 feet wide and 3 feet high. The length can vary according to the amount of leaves used. Once again, the rate of decomposition depends greatly on the size of the material to be composted. Shredding leaves will significantly help to speed the process.
A third option is to incorporate leaves into the garden this fall. After spreading a leaf layer (about 2” thick) over the garden, work the layer into the soil. Then, let nature takes its course. The leaves will decompose over the winter, resulting in rich, dark garden soil by next spring.
So, there are several answers to your all too familiar question. Choose the one that works best for you. Just make sure to enjoy autumn’s last burst of color before it fades away.
written by Bethany A. O’Rear of the Alabama Cooperative Extension System (ACES). She is housed at the C. Beaty Hanna Horticultural and Environmental Center, which is based at the Birmingham Botanical Gardens. Other Garden questions? Call the Master Gardener Helpline, 877-252-4769.
By Andrew J. BarilIt began a week or so ago. In the middle of the night, before the rays of sunlight early Friday morning, I heard a plunk on our roof. This is a sound I know well. My wife and I have been living in our little mountain cabin for almost ten years now. I’ve heard this sound before. For the months of October and November, I will be hearing the plinking of oak acorns and hickory nuts on our metal roof.
Here at our Talladega cabin we have a host of oak trees. We have black, blackjack, cherrybark, chestnut (mountain), northern red, post, southern red, water, white, and willow oaks. We also have mockernut, pignut, and shagbark hickories along with a whole host of additional hardwoods. According to one of Extension’s publications; “Management of Hardwood Forests for Timber in Alabama”, we have around 200 different hardwood species in Alabama, including 28 oaks and 8 hickories. Because Southern Pines so dominate our timber industries, many people tend to overlook hardwoods. However, based on US Forest Service inventory research, hardwoods comprise the majority of Alabama’s standing timber volume.
Most of our forest wildlife friends value these hardwoods for food and shelter. Most of the food value is found in the leaves and seeds. Leaves are eaten mainly by insects that in turn are eaten by other creatures. The seeds are eaten by both small and large alike. How many times have we walked through the woods, picked up seemingly good acorns, only to later find a caterpillar in them? Yes, insects feed on the seeds too! Most often when we in Alabama think of acorns and nuts, we think of deer, turkey, and squirrels. Squirrels need large trees to survive. Squirrels live off seed sources from hickories, oaks, and pines. Deer and turkey are different. They require a variety of habitats. They like both field and forest. During the fall, acorns and nuts provide the needed fat in their diets to help see them through the lean days of winter. Humans can also consume acorns, but they are not as tasty as your cultivated pecans. The meat inside the shell contains higher levels of tannic acid than what we are accustomed. Indians used to collect acorns from white and chestnut oaks along with American chestnuts, black walnut, and wild pecan as a food source for the long winter months. As a side note; within the white oak family (oaks that produce white lumber) the acorns mature in one year, while those in the red oak family (pink lumber) take two years to produce mature acorns. Also, white oak family acorns tend to be larger than the red oak acorns.
Fall is my favorite season of the year. Cool Canadian air, leaves changing on the hillsides, and college football. For me, it all began this weekend with a single plink on my roof.
Andrew J. Baril of the Alabama Cooperative Extension System, C. Beaty Hanna Horticulture & Environmental Center, which is based at the Birmingham Botanical Gardens.
You see them evey year around this time, those pumpkins, squashes, and gourds with bumpy or warty exteriors in shades of green, yellow, orange, and white. Did you ever wonder how they got that way? Well I did, and I've looked into the matter, making some interesting findings to report.
Believe it or not, pumpkins are naturally warty. It was only through years of selective breeding that the smooth-hulled forms we know today came about; as this is the form that most appealed to consumers and thus proved most marketable. Some consumers value the bizarre aesthetic of bumpy pumpkins and gourds however, and so some plant breeders have worked to bring the bumps back. The trouble is, pumpkins in their naturally bumpy form aren't usually uniform in the spread and arrangement of their bumps, and so bumpy cultivars must be crossed repeatedly with one another to enhance their bumpiness into a more regular symmetry. According to Roy Pearman, director of sales and marketing for Siegers Seed Company in Holland, Michigan, it takes at least 10 generations of cross-breeding to produce a pumpkin that's adequately warty. Siegers markets a number of extra-warty pumpkin varieties under its Super Freak label, including 'Gargoyle', 'Knucklehead', and 'Goosebumps'.
Selective breeding isn't the only thing that produces bumpy pumpkins. Those plants afflicted with viral diseases such as cucumber mosaic virus, papaya ring spot virus, squash mosaic virus and zucchini yellow mosaic virus can have their normally smooth fruit transformed into bumpy orbs. These diseases also manifest in stunted vine and leaf growth, plus the namesake light and dark patches on leaf surfaces. These diseases are spread by the feeding of aphids, which transfer the viruses from infected plants to healthy ones. If you don't know whether the pumpkins you're growing are supposed to be naturally bumpy or if you're dealing with a viral infection, the bumps produced as a result of a virus appear to be emerging from the pumpkin's shell while those that occur naturally appear to be resting on the surface.
Mosaic viruses can actually be artificially induced in healthy, smooth-hulled pumpkins to achieve an instant bumpy effect. This practice isn't common, but viruses have found their uses in various other horticultural outlets. The Tulip breaking virus has been used by tulip growers for centuries to produce tulips with multi-colored petals. Tulips normally have petals in just one color, but when their bulbs are infected with Tulip breaking virus, their flowers grow to have stripes and streaks of multiple colors. Some citrus trees have also been artificially dwarfed through forced viral infection, resulting in smaller plants that are easier to harvest.
Back on the subject of pumpkins, squashes, and gourds of the highly textured sort, we have one more pressing question to answer. Can you eat them? For pumpkins and squashes, the answer is yes. The bumpy ornamental varieties only differ from their smooth counterparts in appearance, and are prepared and cooked just the same. Ornamental gourds on the other hand are inedible. You can tell a gourd from a squash by the thickness of the rind. Squashes have thin, soft skin, while gourds thick, hard rinds and a bitter, unpleasant taste. Always be sure to check the exterior skin texture before purchasing squash to eat.
Mitchell Vaughan, Auburn University Department or Horticulture and Extension Graduate Student, Fall 2016
Fall is upon us once again. Although it may not feel quite fall-like to us, deciduous trees and shrubs are starting to reflect the change. Forests throughout the state are already emblazoned with shades or red, yellow, and orange, with more plants transitioning all the time. But some observant individuals may have noticed the fall flush is a bit more ephemeral now compared to years past, with some trees shedding their leaves practically the same instant they change color. What's the cause of these short-lived displays? Is the lack of rainfall in our area to blame? To answer these questions and others, we'll need to take a trip back to middle school biology class and examine the science of why leaves change color in fall.
Deciduous trees and shrubs begin their annual growth in spring, when days become long enough and temperatures become warm enough to support the emergence of overwintering buds into new stems. This growth is typically completed by late June for most trees in the Northern Hemisphere. At this time, trees also begin to set next year's buds, which won't open themselves until they experience the chill of winter followed by the warmth of spring. Once this year's leaves are expanded and next year's buds are set, the tree will begin to manufacture carbohydrates through photosynthesis and store them to support next year's growth.
In late summer or early fall, days become shorter and nights longer. Deciduous trees and shrubs, like most plants, are very sensitive to night length. Once a certain threshold is reached and nights become long enough, these plants respond by forming what's known as an "abscission layer" where the leaves connect with the stems. This corky layer blocks the passage of material into and out of the leaves, including the green pigment chlorophyll. In the absence of chlorophyll, two new pigments become visible, the yellow pigments known as xanthophylls and the orange pigments called carotenoids. These are always present in leaves throughout the growing season, but are normally masked by the green of chlorophyll. Because these pigments are always present in leaves, yellows and golds tend to be fairly constant from year to year. One other group of pigments, the anthocyanins responsible for red and purple fall colors, are manufactured during fall from carbohydrates stored in leaves. These alone are not typically present during the growing season. The amount of these pigments produced depends on the amount of carbohydrates stored in leaves, and so the intensity of reds and purples is more variable in a given year.
Eventually, the abscission layer will thicken and the leaves will drop.
A number of environmental factors impact the intensity and duration of fall colors. Lots of sunlight and low temperatures after the time the abscission layer forms cause the chlorophyll to be destroyed more rapidly, resulting in earlier fall colors. Cool night temperatures combined with abundant sunlight promote the formation of more anthocyanins, and thus more intense reds and purples. Freezing conditions halt the production of anthocyanins, so early frost means an early end to colorful foliage. A growing season with ample moisture that is followed by a dry, cool, sunny fall with warm days and cool (but frostless) nights provides the best weather conditions for development of the brightest fall colors. Lack of wind and rain in the fall prolongs the display; wind or heavy rain may cause the leaves to be lost before they develop their full color potential.
Drought, in particular, can have a severe impact on fall colors. Drought conditions can slow the process of color change, and lead to less colorful, muted displays. Drought stress during the growing season can also sometimes trigger the early formation of the abscission layer, and leaves may drop before they even have a chance to develop fall coloration. Lack of moisture should have less of an impact on yellows and oranges than reds and purples, but these leaves also won't be hanging around too long.
So there you have it. Enjoy the splash of colors while you can, because like fall in the South, it won't last long.
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