Azalea (Rhododendron spp.)-Ovulinia Petal Blight

Early necrotic symptoms are seen on the flower petals.

Cause Ovulinia azaleae, a fungus. The disease is important on many greenhouse-grown azaleas as well as field-grown rhododendron and azalea. Flowers are the only part of the plant affected. Most azaleas and rhododendrons are susceptible and may become infected if weather and inoculum conditions are favorable. The disease develops during rainy periods at flowering time. It overwinters as sclerotia on diseased petals on plants, on the soil surface, or in leaf mulch under bushes. Sclerotia germinate and give rise to stalked, cup-shaped apothecia.

Mature ascospores are discharged from their apothecium. After primary infection, colonization, and the breakdown of flower tissue, numerous conidia form and are spread by splashing rain, insects, and wind.

Symptoms

Infected flowers first show small spots, about 1 mm in diameter, which appear water-soaked. Spots can occur on petals before they are fully open. Spots enlarge rapidly and become slimy. As the disease progress, entire petals become slimy and limp. Infected areas of flowers soon become tan or light brown; eventually entire flowers turn prematurely brown. Infected flowers may last only 2 to 3 days after they are fully opened. Those on lower limbs usually are infected first. Nearly all flowers on a plant become infected when disease conditions are optimum. Infected flowers dry and cling to the plant longer than uninfected flowers. Small, black sclerotia form on infected flowers 8 weeks later. Sclerotia are buried in petal tissue and are most common in the thick portion of the flower throat or tube.
The disease produces no symptoms on the vegetative portion of the plant. Botrytis blight causes spots that initially are similar to those of Ovulinia petal blight but do not enlarge as much or as rapidly. Also, Botrytis blight does not produce slimy petals.

Cultural control

Remove and destroy infected flowers.
Remove and destroy floral debris from the base of plants or pots. Carefully remove 1 inch of the media, mulch, or soil from around base of plants. Replace with fresh, clean mulch.
Avoid overhead irrigation.
Maintain greenhouse humidity below 85%.
Inspect and isolate any new shipments of plants.
Pruning will help improve air circulation and drying conditions. Thin dense plantings and/or remove lower branches where first infections are likely to occur.

 

Posted by The Zeal Group. Call us on 1300882787

Dogwood bush

Growing a red twig dogwood is a great way to add spectacular color to the winter garden. The stems, which are green in spring and summer, turn bright red when the foliage drops off in autumn. The shrub produces creamy-white flowers in spring and berries that ripen from green to white by the end of summer. Both fruits and flowers look good against the dark background of the foliage, but pale in comparison to the brilliant winter display.

Growing a Red Twig Dogwood

Don’t confuse red twig dogwood trees with other dogwood trees. While both the tree and the shrub belong to the Cornus genus, red twig dogwoods never grow to become trees. There are two species of Cornus called red twig dogwoods: Tatarian dogwood (C. alba) and Redosier dogwood (C. sericea). The two species are very similar.

 

Red twig dogwood is one of those plants where more is better. They look fantastic when planted in groups or as an informal hedge. When planting red twig dogwoods, give them plenty of room. They grow up to 8 feet tall with an 8 foot spread. Overcrowding encourages diseases and causes less attractive, thin stems.

Red Twig Dogwood Care

Red twig dogwood care is minimal except for pruning. Annual pruning is essential to keep the brilliant colors of the twigs. The primary goal of pruning red twig dogwoods is to remove the old stems that no longer show good winter color.

Remove about a third of the stems at ground level every year. Cut out old, weak stems as well as well as those that are damaged, discolored, or growing poorly. This method of pruning keeps the color bright and the shrub vigorous. After thinning you can shorten the stems to control the height if you’d like. Cut back the entire shrub to 9 inches above the ground if it becomes overgrown or out of control. This is a good way to quickly renew the plant, but it leaves a bare spot in the landscape until it regrows.

Water weekly in the absence of rain for the first couple of months after planting red twig dogwoods, and cut back on the water once the shrub is established. Mature shrubs only need watering during dry spells.

Feed the plant once a year with a layer of compost or a sprinkling of slow-released fertilizer over the root zone.

 

Posted by The Zeal Group. Call us on 1300882787

Dichondra

Dichondra repens: is a member of the Convolvulaceae family and is known as Kidney Weed. This is an unfortunate common name. Although the leaves are kidney-shaped it is not a weed but a useful Australian native plant.
Dichondra repens is a prostrate perennial that roots at the nodes. The kidney-shaped leaves are about three centimetres across. The flowers are small and inconspicuous.
Dichondra repens is distributed throughout Australia as well as New Zealand .
The species will develop into a dense ground cover but requires reasonable water for maximum coverage.
In some gardens Dichondra repens is grown as a lawn substitute but requires full sun and watering to fulfil this purpose.
It is said the Dichondra repens will invade garden beds. We do not agree with this slander. We welcome Dichondra repens into our gardens as the species does not interfere with other plants. It forms living mulch that inhibits weeds and reduces evaporation.
Propagation is by division.
Sometimes nurseries sell Dichondra repens in punnets.

Plants

Dichondra

Dichondra repens: is a member of the Convolvulaceae family and is known as Kidney Weed. This is an unfortunate common name. Although the leaves are kidney-shaped it is not a weed but a useful Australian native plant.
Dichondra repens is a prostrate perennial that roots at the nodes. The kidney-shaped leaves are about three centimetres across. The flowers are small and inconspicuous.
Dichondra repens is distributed throughout Australia as well as New Zealand .
The species will develop into a dense ground cover but requires reasonable water for maximum coverage.
In some gardens Dichondra repens is grown as a lawn substitute but requires full sun and watering to fulfil this purpose.
It is said the Dichondra repens will invade garden beds. We do not agree with this slander. We welcome Dichondra repens into our gardens as the species does not interfere with other plants. It forms living mulch that inhibits weeds and reduces evaporation.
Propagation is by division.
Sometimes nurseries sell Dichondra repens in punnets.

Plants