Every now and then, I come across a pear or apple tree that has small branches that look like they have been blasted by a torch. Fire blight, as this disease is known, is rampant, and can cause a lot of damage to many loved flowering trees.</p> Fire blight is a disease caused by Erwynia amylovora</em> – a bacteria that enters flowers and other openings of many pome fruit plants. These hosts, which are plants that can be infected with this disease, include susceptible varieties of pear (Pyrus </em>spp.); apple and crabapples (Malus </em>spp.); quince (Cydonia </em>spp.) and firethorn (Pyracantha </em>spp.). Depending on the severity of the disease, it can cause loss of twigs and fruit, branches or in severe cases, the death of the plant.</p> Fire blight is most easily recognized by the “shepherd’s crook” – a curling of the tip of small twigs – and the browning of foliage that looks like it’s been toasted over a flame. In larger branches, cankers develop, resulting in sunken areas along the surface under the bark. Come winter, the branches that have been infected remain attached, giving the tree the appearance of having been burnt in a fire.</p> In the spring, bacteria begin oozing from the cankers and previously infected areas. The bacteria enter the plant through small openings called stomates or through the flowers. Once inside, the bacteria begin to multiply, eventually killing the infected part of the plant.</p> Unfortunately, once a tree is infected with fire blight, it is very difficult to get complete control of this disease. Pruning six to twelve inches below the most visible point of the canker can help, but should be done in the winter, when the bacteria are dormant. It is also important to sanitize your tools while doing so, as the bacteria will transfer between cuts. To sanitize, use a common household cleaner in a 10% solution and wash your pruners off with the solution in between cuts.</p> Chemical controls are an option, but they are costly and less effective for homeowners. In a large orchard operation, they might be considered, but are not on smaller scales.</p> Fire blight is a complicated, frustrating disease to manage. With symptoms that look like a fire burned branches of trees, it causes unsightly damage that is hard to control. Fortunately, it only causes death in extreme infections and can be managed with a little winter management.</p>
After a rain, it’s not uncommon for me to see small white-capped mushrooms popping up in the turf. Many people start worrying – does it mean the grass is unhealthy? Does it mean they’re doing something wrong?</p> Well, in reality, they’re not really bad or good. Mushrooms feed on decaying plant matter aiding in decomposition and returning nutrients to the soil. The mushrooms in the grass are often feeding on thatch – a layer of dead or dying grass tissue resting just above the soil. The mushrooms you see in your lawn are feeding on this thatch.</p> Because of the recent rain, the mushrooms have received signals that environmental conditions are well suited to spread spores for new mushrooms. Usually, the cooler, moister conditions are well suited to sporulation – the spread of new fungi from spores. The caps that appear are designed to spread a multitude of spores across the area, similar to how a tree will drop seeds for new trees.</p> These spores will spread, germinate (just like seeds!) and begin growing hyphae – structures similar to roots in plants. These hyphae will begin feeding on the dead organic matter, breaking it down. When the cooler, wetter weather comes again, the caps will grow, spread spores, and repeat.</p> Fungi are interesting organisms because they have both sexual and asexual forms. The caps are sexual – here is where genetic recombination happens to lead to new, genetically unique colonies. The hyphae are asexual and can reproduce and duplicate, though the subsequent fungi will be genetically identical to the parent.</p> If the mushrooms really are unsightly to you, you can just break the stem and dispose of the caps. However, they usually fade in a few days, so you often can leave them with no concern. They are not edible though, so please do not pick them to eat.</p> Having mushrooms in your turf isn’t a sign of a poorly managed lawn or a failing as a homeowner. It’s merely evidence of a complicated cycle that results in the returning of nutrients to the soil.</p> </p>
In 1999 I attended an international horticultural expo in Kunming, China—Denver’s Sister City. The contrast between the China I found then and the country I visited last month could not be more striking. During my recent trip I passed through four Chinese airports—all of which appeared to be brand new, all of which had stunning architecture and lavish interiors. The city roads, which were thronged with bicycles on my previous visits, were not clogged with Denver-level traffic! The modest cities and towns I had passed through, such as Kunming, have expanded enormously. In 1998, the population of Kunming was under two million people. Two decades later that number has more than tripled to 6.626 million in 2014, compared to the entire population of Colorado, which was 5.607 million in 2017.</p> This truly cataclysmic change has concentrated mostly in the southern parts of China. I have read that the largest migration in human history is likely to have taken place in the last few decades in China, where possibly hundreds of millions of people—mostly youth—have left villages in the north and west to move to cities in the south of China.</p> In Yunnan, much of this change has been driven by tourism. The standard of living in China has risen dramatically, and Chinese are now traveling more than ever. The spectacular mountains, scenery and diverse cultural attractions of Yunnan are bringing vast numbers of domestic tourists along with the steady stream of foreigners who’ve always loved to travel here.</p> The modest and sometimes rather challenging inns of the past have been replaced with numerous luxury hotels in even some of the smallest towns in the high country. Bumpy country roads are now silken, paved highways. A bullet train is being built that will travel from lowland eastern China to the Tibetan border in northern Yunnan. It’s not hard to imagine how this will impact the already booming tourist trade.</p> To someone seeking a flower trip to the Chinese Himalaya, this may sound rather frightening. This is not a pristine wilderness experience! But for most of us, the smoother roads and comfortable hotels are hardly a hindrance. And strangely, the throngs of Chinese tourists seem to stay mostly in the towns or take brief excursions to a tourist destination like Tiger Leaping Gorge or a quick ride up and back on a ski gondola. I led our trusty group of a dozen North American Rock Garden Society members, and we had the whole of Shika Snow Mountain to ourselves one sunny day as we hiked six miles from above 15,000 feet down to 12,000 feet through throngs of unbelievable wildflowers.</p>
Many medicinal plants are easy to grow in Colorado and have incredible healing properties. Horticulturist Blake Burger and horticulture intern Kenna Castleberry pick their top 10 to grow at home.</p>Calendula</strong> (Calendula officinalis)</strong></em> </h2>This flower has anti-inflammatory properties and triterpenoid compounds, which inhibit bacteria. Calendula </em>also has antispasmodic, astringent, antiseptic and detoxifying properties. Ingested, it helps stomach ailments such as gastritis, peptic ulcers, regional ileitis and colitis. It can also be extremely cleansing for the liver. You can use the flowers in tea, oil infusions, or in salves to help with internal and external ailments. Growing tips from staff horticulturalist Blake Burger: Calendula can be started indoors in the spring rather easily. Start inside 6 weeks before last frost and make sure to provide a sunny location for the seedlings to thrive. Plant in full sun after the danger of frost has subsided. To encourage growth throughout the season, fertilize and deadhead.</p>Chamomile (</strong>Matricaria chamomilla</strong></em>)</strong></h2>Chamomile can be taken internally as tea for minor digestive problems. Chamomile can be used as an aromatic, anti-inflammatory, antispasmodic, carminative (digestive aid), and de-stressing nervine. Externally it has been used in hair wash, hair dyes, and for sore skin or eczema. Chamomile is probably the most well-known plant used as a nervine tonic, helping to relieve stress and tension. An essential oil made from the chamomile flowers has been used to help cure diaper rash in newborns. Growing tips from Heather Rhoades of Gardening Know How blog: Plant the chamomile (seeds or cuttings) in the spring. You can grow chamomile in places that have partial shade to full sun. Chamomile does not need a lot of water, so the soil should be mostly dry.</p>Peppermint (</strong>Metha </strong></em>x </strong>piperita</strong></em>)</strong></h2>Because peppermint is antimicrobial, hikers chew peppermint while drinking from a stream to kill microbes in the water. Peppermint is considered a choleretic (bile secretor), antiseptic and invigorator. Tea made from peppermint leaves is soothing for a sore throat, cough, cold. Growth tips from staff horticulturalist Blake Berger: Peppermint prefers a sunny location and moist soil, although it can tolerate part shade. Planting peppermint in a sunny location will increase its production of oils and therefore increase its medicinal potency. Although garden mints have the reputation as an aggressive grower, peppermint isn’t as invasive as some of its relatives. Harvest peppermint leaves and stems often to encourage compact growth. It is ideal to harvest the leaves before and during flowering.</p>Holy Basil</strong> (Ocimum tenuiflorum)</strong></em></h2>Indigenous to India, holy basil is a mild antihyperglycemic, anti-inflammatory, antimicrobial and expectorant. It can be taken internally as tea and is good for treating diabetes, cold or cough symptoms. Internally holy basil can help in treating intestinal tract problems, as well as asthma and reducing fevers. The juice from this plant can be extracted and applied to insect stings, ringworm, and other skin ailments. Growing tips from University of California: Plant in full sun in ¼ inches deep of holes. Keep soil moist but avoid overwatering. Harvest before the plant flowers to avoid flowering and more holy basil growing. This plant continues to grow and flower, so much maintenance is needed. </p>Plantain (</strong>Plantago major</strong></em>)</strong></h2>In Colorado, common plantain is considered a weed. Medicinally, plantain has anti-inflammatory, antibacterial, antimicrobial, emollient and wound-healing properties. Plantain has vitamins A, C, K. You can eat the leaves raw, as they’re more nutritious than other greens and taste similar to swiss chard. However, cooking the leaves will help improve their texture. The leaves can be used externally as poultices to treat insect bites, snakebites, sunburns and cuts. Plantain can also be taken internally as a tea and helps with cold symptoms. Growing tips from Amy Grant of Gardening Know How blog: Plant plantains in sunny areas. Plantains love moist soil, so water without overwatering. Keep plantains about 4 to 6 inches apart. Cover the plant during cold spells to avoid any damage. </p>Hyssop (</strong>Hyssopus officinalis</strong></em>)</strong></h2>Hyssop has astringent, emmenagogue (stimulating menstrual flow), relaxant, diuretic, and wound-healing properties. It stimulates mucus production, and is helpful in soothing sore throats, and coughs. It has also been known to help against asthma. Because it also relaxes muscle, it is helpful in aiding digestive problems. Its antibacterial properties make hyssop a good vermifuge (expels intestinal parasites). Hyssop essential oil has medicinal properties, but has also been linked to epileptic seizures, and should be taken with precaution. Growth tips staff horticulturist Loddie Dolinski: This plant is pretty hardy and doesn’t need too much water. Once it’s been established it merely needs normal watering. It should be grown in full sun. Hyssop gets no pests after it’s grown.</p>English Lavender (</strong>Lavandula angustifolia </strong></em>“Vera”)</strong></h2>Lavender has analgesic (pain relieving), antidepressant, antifungal, antioxidant, antiviral, aromatic, cholagogue (something that stimulates the flow of bile from the liver) and cicatrisant (wound healing) properties, as well as many others. It also acts as an effective sleep aid and can be combined with valerian or chamomile in tea, or merely sprinkled onto the sheets as lavender oil, or dried flowers can be sewn into a pillow. Lavender is also powerful at curing headaches. Growth tips from staff horticulturalist Angie Andrade: lavender angustifolia </em>or English Lavender prefers full sun and slightly alkaline soils which is perfect for our Colorado gardens. Be careful when buying Lavender because French and Spanish Lavender are not hardy here. </p>Hops </strong>(Humulus lupulus)</strong></em></h2>Hops is known to have soporific, anti-spasmodic, diuretic, and nervine properties. The bitter properties of hops stimulate digestion. Hops has estrogenic properties and shouldn’t be given to young children. The cones can promote good night’s sleep. Growth tips from Blake Berger: Plant a rhizome rather than growing from seed. A hops rhizome should be planted in early spring when the soil can be worked. Keep the rhizome moist but not in boggy soil. Once sprouts rise from the soil, pick the strongest and healthiest and start to train up a trellis. Cut back the weaker ones. Once established, water several times a week. Keep the base of the plant relatively thinned out to prevent powdery mildew.</p>Hawthorn </strong>(Crataegus ambigua)</strong></em></h2>The bark has astringent properties which helps in treating fevers. Hawthorn’s an antispasmodic, cardiac (promotes heart health), diuretic and vasodilator. Hawthorn can help fight heart weakness, spasms, and murmurs. It also balances blood pressure and can be a sedative on the nervous system. Growing tips from staff bonsai specialist Larry Jackel: Hawthorn is vulnerable to fireblight, so prune in the winter, sterilizing the tools between uses. You can grow these from seeds or cuttings. The berries are known to germinate quite quickly. Once the plants have been established, only basic maintenance is needed as hawthorns are hardy. Hawthorns are known to have extra sprouts around the base of the tree, so you can either remove those or have them sprout into separate plants.</p>Elecampane </strong>(Inula helenium)</strong></em></h2>Elecampane is a tall bushy-like plant that gives height to any garden. It has beautiful sunflower-like flowers that attract all sorts of pollinators. Medicinally, elecampane has expectorant, choleretic, cholagogue, antimicrobial, vermifuge and diuretic properties. It can be taken internally as a tea, made from the root to treat colds, coughs, asthma, loss of appetite, intestinal worm and digestive problems. Decoctions and tinctures are also made from the root and can help treat cold and cough symptoms. Elecampane can be applied externally to help with skin ailments such as eczema and itching. Growing tips from Growing Hermione’s Garden blog: Grow this plant in partial sun with moist, well drained-soil. Minimal maintenance is needed for this plant. It is a perennial. </p>
One of the most frequent questions I get around this time of year is “what is growing on my leaves?” while being handed a hackberry leaf with knobs on the back. These knobs are galls – abnormal growths on leaves and stems with a number of different causes, mainly insects and diseases.</p> In the case of the hackberry</a> knobs, these are hackberry nipple galls caused by a psyllid – a tiny plant-feeding insect. The galls themselves are a plant response to the feeding of the larvae, forming a protective covering over the insect as it matures. Fortunately, this psyllid doesn’t affect the tree dramatically, just makes it unsightly. While control is possible, it is challenging and impractical.</p> Most galls are formed by an increase of hormones stimulating cell growth. When bacteria, viruses or fungi enter the plant, the response is to “seal off” the area with a mass of cells, forming a gall. With insects and mites, the response is similar, though the insect is often encased in the gall until it emerges.</p> Insect-based galls are challenging to deal with, as the galls typically protect the insect until they emerge as adults and fly away. With most disease-borne galls, the best management strategy is to collect and remove the leaves from beneath the infested plant in the fall. Doing this helps break the disease cycle. Since galls typically do not cause massive damage to the tree, pruning to remove the unsightly growths is probably the most efficient method of control.</p> All in all, galls are nothing to be concerned about. They are simply the plant trying to defend itself from an invader.</p>
Plastic straws are OUT! As an article in the Denver Post</a> recently illustrated, Colorado restaurants are joining a national and even international trend to replace single-use plastic straws with either compostable and/or paper straws. The Gardens’ Offshoots Café and Hive Bistro</a> at the York Street location recently swapped out plastic straws in favor of biodegradable ones, expanding their list of compostables to include all cups, plates, cutlery and paper products.</p> </p> Not only do plastic straws not decompose in landfills, but they are likely to find their way into streams and rivers, eventually contributing to the growing problem of plastic contamination</a> on beaches and in oceans. In an effort to address the issue, Seattle became the first U.S. city to ban plastic straws (on July 1) and its homegrown café chain Starbucks recently announced it will eliminate all plastic straws by 2020.</p> Closer to home, the Gardens is working with concessioner Catering by Design on this and other initiatives to make “green” dining the norm – for example, in May the Gardens stopped selling bottled water</a>. </p> So where do the compostable straws end up? The Gardens has a three-bin waste system at York Street to facilitate recycling and composting. Onsite diversion of plant material, food and other biodegradable waste generates several tons of compost that can then be used as a soil amendment – in our own gardens and elsewhere.</p> </p>
</p>It’s the peak of summer here at our York Street location, and we are heading into the busiest weeks of the annual Summer Concert Series</a>. Even for seasoned Denver concert-goers, there’s no venue in town quite like the Gardens. With somewhat unique restrictions on what you can bring, what you can’t bring, and what your evening will look like, we want to share with you our best tips for ensuring your concert experience is a comfortable one.</p>BYOB</strong>Perhaps the most dramatic difference between the Gardens and other local concert venues is that we do not sell alcohol onsite. However, you are welcome to bring your own! Concert-goers can bring their own beer, wine and other alcoholic beverages (coolers are permitted, as well). Of course, we always recommend drinking in moderation, so if you are arriving by car, make sure you designate a sober driver!</p>Bring short chairs, or just rent or buy one of ours</strong>To provide a great viewing experience for all our guests, we do not permit any chairs with a total height taller than 28” inside the property. Alternately, if you don’t want to mess with dragging your own chairs along, stop by the bright green chair rental tent at the north end of the UMB Bank Amphitheater tent and rent one from us for $10. This year, we also have some chairs for sale for $70 + tax. Don’t wait too long though – we often sell out before the concert begins.</p>Know what you can bring, and what you can’t</strong>We want you to have a leisurely evening with lots of creature comforts, but we do prohibit some items from entering the Gardens on a concert date to ensure a pleasant experience for everyone. As part of our commitment to safety, every bag, cooler and wagon will be screened upon entry. Prohibited items may be confiscated, so we recommend leaving those at home to begin with. Here is a list of accepted and prohibited items</a>. </p>Want a prime seat? Get in line early. </strong>While the gates open at approximately 5:45 p.m., guests who are eager for a prime seating location often line up hours earlier. While we think there isn’t really a bad seat in the house, we suggest arriving early with a book or a knitting project if a front-and-center seat is what you have in mind.</p>Try Anna’s Overlook for spacious seating</strong>On the other hand, if you’d rather not squash into the UMB Bank Amphitheater with hundreds of strangers, the grassy slope west of the Science Pyramid offers excellent sound and plenty of space to spread out. You may not see the performers, but you’ll hear their serenades just fine.</p>Order a picnic dinner in advance</strong>Both Offshoots Café and the Hive Garden Bistro are open for dinner</a> each concert evening. You can also visit the new hot dog cart</strong> in Oak Grove. If you’d rather not wait for your food during the concert, pre-order a Summer Picnic Box</a>. </p>Dress for success</strong>Our concerts go on rain or shine, so make sure you check the weather in advance. Ponchos, sunscreen, sunglasses, hats, blankets, sweaters, jackets – we usually see them all in the course of a concert season.</p>Severe weather threats</strong>The Gardens will be evacuated when lightning, hail, high winds or other severe weather threats are in the immediate vicinity, and the show will be delayed/stopped until the threat of severe weather has cleared. A banner alert will be posted on this website with updates, and staff will communicate via bullhorns to keep concert-goers informed. We thank you for your participation in keeping everyone safe! </p>Take in your surroundings</strong>Feel free to wander the Gardens as you like throughout the concert. The Summer Concert Series is not just about incredible musical talent; it’s about showcasing it in the spectacular setting of a horticultural wonderland. Many of our gardens are in peak bloom, and you may be lucky enough to catch a breathtaking sunset while you’re here!</p>Learn everything you need to know about attending a concert at the Gardens on this Plan Your Visit page</a>.</p> </p>
Kenna here, the medicinal plant intern at Denver Botanic Gardens. I’m excited to announce the newly publicized medicinal plants virtual tour on the Gardens Navigator website! In creating this virtual tour, I hope to bring more awareness to medicinal plants and help dispel the reputation of "pseudo-science" that herbalism often has.</p> Here is the Medicinal Plants Tour</a></p> I chose 30 plants, ranging from the tropics to the tundra, from cattails to Calendula</em>. I also picked plants that were in as many of the different sub-gardens within the Gardens as possible, so that those following this tour on foot would see the variety in color and scent these plants are known for.</p> On this tour you’ll find extensive research on both the stories and science behind each plant. Read about the mythology surrounding Alder trees while also learning about the chemicals that make them so medicinal. I’ve even added practical recipes to go along with each plant that you can try at home. Included in each exhibit are growth tips provided by some of our staff horticulturists for growing these plants successfully in the ever-changing Colorado climate.</p> On the introduction page of this tour, you’ll find the link to the Denver Medicinal Plant Society (DMPS), which I worked with in my research. On the DMPS website there are even more recipes and history on medicinal plants not covered in this tour, as well as more scientific evidence behind why medicinal plants "work."</p> On the introduction page you’ll find a link to my YouTube channel, where I’ve filmed short videos of how to make these recipes. Each video is no longer than three minutes and gives practical and easy ways to make old classics and new favorites, such as a comfrey salve. Join me as I show you how to infuse</em> more medicinal plants into your life. Get it?</p> Okay, joking aside, you’ll find references and acknowledgements on the front page as well. I have done extensive research to make sure this tour is as accurate and informative as possible. With more than 100 cited references, I’m happy to say that everything you learn about on this tour came from a credible source. So, what are you waiting for? Take our virtual tour today!</p>
When it comes to pest management, Denver Botanic Gardens ascribes to Integrated Pest Management (IPM) strategies to manage and control pest populations. One of the critical components of IPM is biological control – the use of specific organisms (often called natural enemies or biological control agents) to control pests. A high volume of research goes into developing biological control; this may include assessing how effective the natural enemy is, what impacts it may have outside of the desired target and ideal conditions for use. Biological controls aren’t exclusive to insects, but they are the easiest to work with. Fungi, bacteria and nematodes are all also used.</p> The Gardens predominantly uses biological control within the greenhouses. This reduces the reliance on pesticides, though some are still used when necessary. While the overall goal is to have a sustainable population, the greenhouse staff schedules regular releases of a range of natural enemies to prevent the build-up of pest insects – including aphids, whiteflies and spider mites.</p> The natural enemies arrive live. Some are in the pupal stage contained in small containers on cards or are adults in vials or drawstring bags. The cards are hung throughout the greenhouse, especially near plants that have infestations or are known to. The adults are released from their containers and fly off in search of prey. Depending on the natural enemy’s strategy, they will either eat the target insect or lay eggs on it. In both cases, the target insect is killed, protecting the plant.</p> For example, mealybug destroyers, Cryptolaemus montrouzieri,</em> will fly in search of mealybugs, and will consume the entire insect. Mealybug destroyer eggs are laid near populations of mealybugs, and the larvae will also search out the pest insect. Encarsia formosa</em>, a parasitoid wasp, will search out whitefly adults and lay eggs inside. After the eggs hatch, the wasp larvae kill the whitefly by consuming the guts, forming a whitefly mummy. The wasps then pupate and emerge as adults, ready to begin the cycle anew.</p> Biological control isn’t limited to just plant production – there are plenty of examples of biological control outside in the gardens. One of the most easily recognized are ladybugs – both the adults and the larvae will feed on aphids. Lacewing larvae are also well known for feeding on insects, including aphids and mites.</p> Biological control is challenging to release out into the gardens because we have no control over where the insects go. Instead, it is far easier to provide habitat for natural enemies. Knowing their host plants, environmental needs and providing water will bring natural enemies into your garden!</p>
