Begonia Aster Yellows Control: Treating Begonia With Aster Yellows



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By: Amy Grant

Begoniasare gorgeous colorful blooming plants that can be grown in USDA zones 7-10.With their glorious blossoms and decorative foliage, begonias are fun to grow,yet not without their issues. One problem the grower may encounter is asteryellows on begonias. The following article contains information on how toidentify a begonia with aster yellows disease and aster yellows control.

What is Begonia Aster Yellows Disease?

Asteryellows disease on begonias is caused by a phytoplasma (formerlyreferred to as a mycoplasma) that is spread by leafhoppers.This bacterium-like organism causes virus-like symptoms in a huge host range ofmore than 300 plant species in 48 plant families.

Symptoms of a Begonia with Aster Yellows

The symptoms of aster yellows vary depending upon the hostspecies combined with the temperature, age and size of the infected plant. Inthe case of aster yellows on begonias, the first symptoms appear as chlorosis(yellowing) along the veins of young leaves. The chlorosis worsens as thedisease progresses, resulting in defoliation.

Infected plants do not die or wilt but, instead, maintain arather spindly, less than robust growth habit. Aster yellows may attack part orall of the plant.

Begonia Aster Yellows Control

Aster yellows overwinters on infected host crops and weedsas well as in adult leafhoppers. Leafhoppers acquire the disease by feeding onthe phloem cells of infected plants. As early as eleven days later, theinfected leafhopper can transmit the bacterium to plants it is feeding on.

Throughout the lifecycle of the infected leafhopper (100days or longer), the bacterium multiplies. This means that as long as theinfected leafhopper lives, it will continuously be able to infect healthyplants.

The bacterium in the leafhoppers can be quelled whentemperatures surpass 88 F. (31 C.) for 10-12 days. This means that hot spellslasting for more than two weeks reduce the chances of infection.

Because weather cannot be controlled, another plan of attackmust be followed. First, destroy all susceptible overwintering hosts anddestroy any infected plants. Also, remove any weed hosts or spray them prior toinfection with an insecticide.

Place strips of aluminumfoil between the begonias. This is said to aid in control bydisorienting the leafhoppers with the reflection of the light playing againstthe foil.

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Anthracnose on Deciduous Trees

Shade trees commonly affected by anthracnose are ash, dogwood, elm, hickory, maple, oak, sycamore, and walnut. The fungi that cause it, mostly from the family Gnomoniaceae, vary depending on the tree species.

Anthracnose can affect the buds of a tree early in the season before it has grown any leaves. When the buds or the tips of twigs die as a result, it might look like frost injury, which can make it tricky to diagnose anthracnose at this stage.

The symptoms of anthracnose are easier to identify once the tree has leafed out. You’ll notice small, circular or irregularly shaped dark or brown dead spots on the leaves, dead leaf margins and tips, and large dead blotches along the leaf veins or in-between the veins.

When the tree is heavily infected early in the season, the leaves may be distorted, shrivel and fall off prematurely. Sometimes the foliage regrows after defoliation. Other symptoms are girdled dead twigs with areas of sunken bark.

To determine whether it’s anthracnose, take a look at the underside of infected leaves with a magnifying glass. You’ll see fungal fruiting structures that protrude like pimples, especially along the leaf veins. There are similar fruiting structures at the tips of dead twigs.

Anthracnose overwinters in infected branches, twigs, and leaves. In the spring, wind carries the pathogens to young leaves and twigs, where it forms new spores. These spores then move by wind or water, splashing to neighboring foliage, infecting it and thus continuing the disease cycle.

Cool spring weather with temperatures between 50 and 55 degrees F is especially conducive to spreading the disease.


Impatiens, Busy Lizzy, Touch-me-not, New Guinea Impatiens, Sunpatiens - Impatiens

Impatiens Double Fiesta 'Bonita White' Picture courtesy www.ballstraathof.co.za Condensed Version:

Gardeners have always loved Impatiens for shady gardens for their ease of growth and beautiful array of colours, but today gardeners are spoilt for choice when it comes to Impatiens, and breeders continue to surprise us with brilliant new garden hybrids. Some can even be grown in full sun and take heat and humidity.

The old-fashioned shade-loving Impatiens, (Impatiens walleriana) will flower all summer long, and available in colours from white through every shade of pink and magenta to oranges and reds as well as those with starry centres and swirls, and lovely selections of double-flowered varieties. Most modern varieties are dwarf and compact growing 15 to 30cm tall and 10 to 15cm wide. These are perfect border and in pots, hanging baskets, window boxes, in massed beds and underneath trees, for a dazzling display.

Because New Guinea Impatiens can take a lot more sun than the ordinary impatiens they are even more versatile in the garden. Their flowers are also a lot larger than ordinary impatiens and come in a vast colour range, covering every shade of red, orange, pink, lavender and white. They are also a lot taller, growing from 30 to 70cm in height. Many varieties also have interestingly coloured foliage in tones of green, together with plum and bronze, or golden to clear yellow. Their bright leaves and big, showy flowers will liven up any spot in the garden, and they are stunning in hanging baskets, window boxes and containers of all kinds.

Sunpatiens are grown the same as New Guinea Impatiens but thrive in full sun and hot, humid weather, as well as in semi-shade. They come in an excellent colour range, making them excellent container and bedding plants for long lasting colour. Sunpatiens also come in three sizes: compact, spreading, and vigorous. Both the compact and spreading plants are perfect for containers. The compact ones can fill in gaps when combined with other annuals while a single spreading one will fill out a hanging basket or pot spectacularly, or grow quickly and flower abundantly in garden beds.

Caring is easy, as long as you keep the plants well-watered throughout the hottest parts of the year. They are all tender to frost, and in cold regions are grown as summer annuals which are planted out in spring after all danger of frost is over. In warmer regions they can be grown year round, and they will perform as short-lived perennials.

The most important tip is to ensure that the soil has perfect drainage, so plant in a light, moist, well-drained soil, and for impatiens planted in containers, use a good quality commercial potting soil that contains peat moss and either perlite or vermiculite.

It is also vital to allow for plenty of air circulation around the plants, as this helps prevent fungal infections. Overcrowding can be fatal, so space your plants correctly.

Even though the plants love regular watering, the soil must not remain soggy, and to help prevent diseases it is better to avoid overhead watering, and to water early in the day to ensure that the plants are totally dry by nightfall.

Use fertiliser sparingly, as too much fertiliser weakens plants and makes them more susceptible to disease. Feeding is not really necessary for plants in garden beds, but potted specimens can be fed about every 6 to 8 weeks, using a liquid fertiliser for flowering plants, at half the recommended strength.

Impatiens 'Sunpatiens' Picture courtesy www.nuleaf.co.za Full Version:

Description, History & Interesting Facts:

Gardeners have always loved Impatiens for shady gardens for their ease of growth and beautiful array of colours, but today gardeners are spoilt for choice when it comes to Impatiens, and breeders continue to surprise us with brilliant new garden hybrids. Some can even be grown in full sun and take heat and humidity, much to the delight of gardeners around South Africa. These exciting varieties ensure that Impatiens remains one of our most popular summer bedding plants.

We have always relied on the commonly called “Busy Lizzy” or “Touch-me-not” (Impatiens wallerana) for their ease of growth in difficult shady areas, as well as for their wide range of colours. Then the irresistible (Impatiens hawkeri,) commonly called “New Guinea Impatiens” hit the shelves, and caused quite a stir! These were taller growing Impatiens with larger flowers in vibrant colours, and often with colourfully variegated leaves, and because they could take a lot more sun than ordinary Impatiens, became an instant hit. Today we are also blessed with a relatively new hybrid called “Sunpatiens” (Impatiens hawkeri hybrid) which grows in full sun or semi-shade, and even thrives in hot, humid weather, greatly expanding the area in which Impatiens can be grown in South Africa.

Impatiens is a large family of plants which is widely distributed in the subtropics and tropics of Asia and Africa, where they never stop flowering. New Guinea Impatiens is native to New Guinea, and all our modern hybrids are bred from species collected there and later in Java and the Sulawesi Islands. Sunpatiens is a hybrid bred by the Japanese seed company Sakata. It is a careful combination of wild “traditional” impatiens (from a plant species native to Indonesia) with the larger, heat-loving Impatiens hawkeri, native to New Guinea.

Impatiens Super Elfin 'Paradise Mix' Picture courtesy www.ballstraathof.co.za In the Garden:

Impatiens really give you bang for your money and are quite reliable in the garden as long as they can be watered regularly, so group them together with other water-loving plants. Water is becoming a real luxury in South Africa, and more and more expensive, so be realistic when planning your flower garden by grouping plants together according to their watering requirements. Use smaller areas of the garden for those plants you simply love but which will require regular watering. Grouping them together will not only make watering your garden much easier, but it’s also just common sense.

The old-fashioned shade-loving Impatiens, (Impatiens walleriana) will flower all summer long, and thousands of varieties are available, with colours ranging from white through every shade of pink and magenta to oranges and reds as well as those with starry centres and swirls. Lovely selections of double-flowered varieties that look just like miniature roses are especially beautiful in containers. They vary in height but most of the modern varieties are dwarf and compact growing 15 to 30cm tall and 10 to 15cm wide. These are perfect border and container plants, so plant them everywhere in the shade in pots, hanging baskets, window boxes, in massed beds and underneath trees, for a dazzling display all summer long. The fully blown seedpods suddenly pop open at even the lightest touch, spreading the seeds far and wide, hence their common name “touch-me-not.” This fascinates children and they will run around popping the seeds with glee.

Because New Guinea Impatiens can take a lot more sun than the ordinary impatiens they are even more versatile in the garden. Their flowers are also a lot larger than ordinary impatiens and come in a vast colour range, covering every shade of red, orange, pink, lavender and white. They are also a lot taller than ordinary impatiens, growing from 30 to 70cm in height. Many varieties also have interestingly coloured foliage in tones of green, together with plum and bronze, or golden to clear yellow. Their bright leaves and big, showy flowers will liven up any spot in the garden, and they are stunning in hanging baskets, window boxes and containers of all kinds, requiring little maintenance, and no deadheading.

Sunpatiens come in an excellent colour range and thrive in full sun and hot, humid weather, but can also be grown in semi-shade, making them excellent container and bedding plants for long lasting colour. Sunpatiens also come in three sizes: compact, spreading, and vigorous. Both the compact and spreading plants are perfect for containers. The compact ones can fill in gaps when combined with other annuals while a single spreading one will fill out a hanging basket or pot spectacularly, or grow quickly and flower abundantly in garden beds.

Impatiens 'Sunpatiens' Picture courtesy www.tuberflora.co.za Cultivation/Propagation:

Caring for Impatiens is easy, as long as you keep the plants well-watered throughout the hottest parts of the year. They are all tender to frost, and in cold regions are grown as summer annuals which are planted out in spring after all danger of frost is over. In warmer regions they can be grown year round, and they will perform as short-lived perennials.

The most important tip to growing healthy Impatience is to ensure that the soil has perfect drainage, so plant them in a light, moist, well-drained soil, and for impatiens planted in containers, use a good quality commercial potting soil that contains peat moss and either perlite or vermiculite.

It is also vital to allow for plenty of air circulation around the plants, as this helps prevent fungal infections. Overcrowding can be fatal, so space your plants correctly.

Even though the plants love regular watering, the soil must not remain soggy, and to help prevent diseases it is better to avoid overhead watering, and to water early in the day to ensure that the plants are totally dry by nightfall.

Use fertiliser sparingly, as too much fertiliser weakens plants and makes them more susceptible to disease. Feeding is not really necessary for plants in garden beds, but potted specimens can be fed about every 6 to 8 weeks, using a liquid fertiliser for flowering plants, at half the recommended strength.

Impatiens, Busy Lizzy, Touch-me-not plant (Impatiens walleriana) is not suited to very dry or humid regions and thrives in semi-shade to light sunshine. In hotter regions, protect them from the fierce midday sun and excessive winds, which will cause the flowers and leaves to scorch.

New Guinea Impatiens (Impatiens hawkeri) will grow and bloom for a very long time in warm regions and can be planted out at any time, but if you live in cold and frosty regions don't rush to plant New Guinea impatiens out too early in spring, as the plants prefer consistent daytime temperatures between 22 and 29°C. New Guinea Impatiens love to receive full morning sun or bright shade throughout the day, and really don't like total shade. In very hot regions, protect them from the fierce midday sun and excessive winds, which will cause the flowers and leaves to scorch.

Sunpatiens are a revolutionary new hybrid impatiens which is grown and propagated in the same way as New Guinea Impatiens. It can take full sun or semi-shade, and thrives in heat and humidity. The thicker petals and tough foliage are less prone to disease, and their strong sturdy stems tolerate adverse weather conditions. There is no need to pinch off old flowers as they fall of cleanly.

Propagation:

Impatiens walleriana seed needs quite high soil temperatures to germinate and can be sown indoors in late winter and spring in a germination tray at temperatures between 22 and 25°C. If you do not have a germination tray sow seeds in late spring or early summer. Do not cover the seeds with soil as they require good light to germinate. Cover the seed trays with plastic or glass to maintain 100% humidity and place them in good light but out of direct sunlight. Remove the glass or plastic when the seeds have germinated. Seeds will take from 7 to 14 days to germinate and will start blooming about 10 to 12 weeks after sowing.

New Guinea Impatiens (Impatiens hawkeri) and Sunpatiens seed is harder to obtain but if you do find some, germinate it in seedling trays at soil temperatures between 22 and 28°C - the perfect temperature being 25°C. Impatiens need very good light to germinate so do not cover the seeds with soil, and place the trays in bright light with no direct sunlight. Germination will take 7 to 14 days and the plants will bloom in about 12 to 16 weeks. Plants are also propagated by cuttings taken in spring or summer but most cultivars are patented, and taking cuttings for resale, unless you are a licensed propagator, is illegal.

Problems, Pests & Diseases:

Although relatively trouble-free, Impatiens can be affected by some disease and pest problems. However, many of these can usually be avoided through good cultural practices.

Fungal diseases that affect impatiens include root, crown and stem rots, powdery mildew, grey mould and downy mildew. Many growers do not recommend the use of fungicides to treat blights and mildews on impatiens because the fungal spores appear on leaves and petals, and chemicals can damage these delicate plants. Rather, they recommend proper growth and sanitation methods which prevent fungal pathogens from attacking your impatiens in the first place.

Bacterial soft rots are caused by a number of organisms. Affected plants turn brown and mushy near the soil. Seedlings collapse and plants grow slowly. Bacterial leaf spots start as small, water-soaked areas that may encompass the entire leaf.

Root rot and crown disease generally affects impatiens planted in poorly drained soil or pots without sufficient drainage. Dull foliage, wilting and yellowing are the first aboveground symptoms of root and crown disease. Seedlings don't emerge and rot in the soil, and in established plants the stems turn soft and dark, and stunting and death quickly follows. Discard all the plants carefully in garbage bags to prevent the disease spreading, and start afresh. Do not, however, plant again in the same spot for a couple of seasons, since this disease remains in the soil. Good soil drainage and air circulation goes a long way to preventing these diseases.

Botrytis blight, also known as “grey mould” is a fungal disease caused by several species in the genus Botrytis. It affects the buds, flowers, leaves, and bulbs of many plants including: impatiens, African violet, begonia, chrysanthemum, cyclamen, dahlia, geranium, lily, peony, rose, and tulip. The extent and severity depends on weather conditions and cultural practices. This disease is the primary cause of decay in cut flowers, causing the buds and flowers to develop abnormally and turn brown. Flowers may have irregular flecks and brown spots and older flowers tend to rot quickly. The disease often occurs when the weather is warm and humid, but the nights are still a bit chilly. Soft, brown spots appear on the leaves, stems and affected parts may be covered with a grey mould. To help prevent this, don't plant Impatiens, and especially New Guinea Impatiens out too early in spring.

Botrytis fungi overwinter as sclerotia on dead plant debris in the garden, and in the spring, spores form and spread by wind or splashing water to infect dying, wounded, or extremely soft plant tissues. Fungal mycelial strands (web blight) from previously infected plant parts can grow onto healthy plant parts and infect them. The fungus is capable of invading tissue during all periods of the growing season and multiplies rapidly in declining foliage, hence, the need for good sanitation.

To help prevent infection, allow for good air circulation around the plants, do not overfeed, and especially with fertilisers high in nitrogen, water early so the plants have enough time to dry off completely, and avoid overhead watering. If weather conditions are ideal for the appearance of this disease, preventative spraying is best. Otherwise, start spraying immediately with a suitable fungicide like copper sulphate once the infection is noticed, repeating as directed on the product.

Powdery mildew is a common garden disease which is easy to spot, displaying as a powdery white or grey coating on the leaves. Eventually, affected plants develop distorted or stunted growth and the leaves drop. To help prevent this ensure that the plants receive sufficient sunshine, and that they are correctly spaced. Try to water in mid-morning so the leaves have ample time to dry before evening falls. Keep the area around the plant free of leaves and other debris, and immediately infection is noticed, start spraying with an organic fungicide like neem oil, every 7 to 14 days, until the disease is eradicated.

Downy mildew appears as a white, lavender, or purple dusting on leaves, usually appearing when weather conditions are adverse - like rainy, hot or humid weather, combined with chilly evenings. These fluctuations in temperature, combined with heavy rain, seem to be a trigger for downy mildew.

Fasciation on impatiens is a condition that it not completely understood but is thought to be caused by bacteria, viruses, or possibly genetics. Stems are abnormally flattened and appear to have grown together. Shoots are short and grow in swollen clumps, and the leaves are plentiful but abnormally small. The bacteria that cause fasciation lives in dead and decaying leaf and flower material, so sanitation practices will help greatly in prevention.

Necrotic spot virus and tomato spotted wilt virus are the two main viruses that affect impatiens. Symptoms include black ring spots, mosaic patterns on the leaves, and dead tissue that is brown or tan. Flower colour is mottled and the leaves become distorted and yellow. Stems develop black areas or lesions and plants become stunted. There is no cure for either of these viruses once they have infected the plant, and they should be removed and disposed of carefully.

Insects can also attack Impatiens, but these are most prevalent when the plants are grown under cover. Watch out for snail and slugs who love Impatiens growing anywhere. Aphids damage impatiens by sucking out the plant juices, and similarly, plants are often affected by tiny sap-sucking spider mites found on the undersides of leaves, and which are most prevalent in warm, dry conditions. Treat both these pests by spraying the plant with an insecticidal soap spray. Watch out for whitefly, which suck the plant juices, leaving yellow stippling marks in the leaves. Thrips also suck the plants sap and are found on the undersides of the leaves. Mealybugs are yet another sap-sucking insect found on the upper surfaces of the plants.

Although Impatiens is listed as a non-toxic to dogs and cats, keep in mind that even non-toxic plants can cause vomiting in humans and animals if ingested.


Watch the video: Begonia Nonstop Joy, what do nonstop begonias look like, how to feed begonias


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