TopVeg – growing veg,fruit&herbs

October 3, 2009

Courgette Mildew shortens season.

Filed under: pests&diseases — Tags: , — TopVeg @ 12:30 pm

Mildew in courgettes shortens the growing season.

mildew-on-courgette-leaf

mildew-on-courgette-leaf

The courgette Venus F1 hybrid has succumbed to courgette and has died very quickly.

mildewed-courgette-plant

mildewed-courgette-plant

The courgette Dundoo F1 is tolerant to powdery mildew and is still looking well, & producing courgettes, although it is planted next to a Venus which is covered in mildew spores.

mildew-resistant-courgette

mildew-resistant-courgette

The Dundoo courgette plants have given huge yields of glossy, dark green courgettes. As well as being mildew tolerant it has the added advantage of a large open bush habit which makes picking easy.

Although mildew has shortened the season in the Venus courgettes, the Dundoo season continues & will be prolonged by covering it with a cloche to protect from the frost.

April 19, 2009

Powdery Mildew in Courgettes

Filed under: pests&diseases — Tags: , , — TopVeg @ 4:51 pm

Powdery mildew is a fungal disease which flourishes on courgettes when the weather is warm and dry.

mildew-on-courgette

mildew-on-courgette

Infected courgette plants are covered in a greyish-white mould, mainly on the upper surface of the leaves and young shoots.

courgette-in-flower

courgette-in-flower

CONTROL OF POWDERY MILDEW

* Attacks of powdery mildew occur in dry seasons and are worst in sheltered gardens.

mildewed-courgette-plant

mildewed-courgette-plant

* It is not known how the fungus survives between crop seasons, & crop rotation and many other cultural practices seem to have little effect on the incidence of powdery mildew.
* Courgettes need fertile soil. Plants grown in poor soil, without correct applications of fertiliser, will develop powdery mildew before well fed plants. Healthy, vigorous leaves and stems are less prone to infection.
* Grow Mildew tolerant varieties of courgettes, such as Dundoo, Soleil

mildew-resistant-courgette

mildew-resistant-courgette

* Chemical sprays are available to control powdery mildew in courgettes, always follow the instructions on the packet.

February 23, 2009

American Gooseberry Mildew

Filed under: pests&diseases — Tags: , , — TopVeg @ 7:17 pm

strong>American Gooseberry Mildew (latin name – Sphaerotheca mors-uvae) is a common fungal disease of gooseberries and blackcurrants. Red and white
currants may also be attacked.

Signs of American Gooseberry Mildew in Gooseberries:
A powdery, white coating appears on new shoots, spreading to young
leaves and, eventually, the berries. Later these patches form a
felt-like mat and turn brown. Leaves curl up and fall off. The
gooseberries are small and may be covered with brown felt.

American Gooseberry Mildew occurs:

* in crowded plants
* humid conditions
* areas of coastal fog
* when the soil around the roots is dry
* where irrigation is by overhead sprinkling
* in crowded plants

Life cycle of American Gooseberry Mildew
The fungus overwinters in dormant buds. These produce infected shoots in
spring which spread the disease by releasing wind-blown spores.

Prevention and control:
* select a suitable planting site which is sunny and not humid
* allow plenty of space between bushes
* prune to keep bushes open and airy
* avoid too much nitrogen-rich fertilizer which will produce soft
shoots, more susceptible to infection
* cut out and burn infected shoots in July & September
* water to keep the soil around the roots moist
* use a mulch

mulch-on-raspberries

mulch-on-raspberries

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* grow mildew resistant varieties such as Invicta
* chemical control - spray with a sulphur fungicide - but check
that the chemical is safe on the variety by spraying a small area
and waiting for 24 hours to see if the leaves start to curl.
Spray just before flowers open, after fruit set and again 2-3
weeks later. Spray flowering crops at dusk when bees are not
active. Do not use in full sun. Read the label and follow the
instructions.

August 8, 2007

Downy mildew on Leeks

Filed under: root veg — Tags: , , — TopVeg @ 7:21 pm

Downy mildew (latin name – Peronospora destructor) develops on leek (Allium porrum) when humidity is high and night temperatures are low. These conditions are usually seen in the autumn.

Downy mildew is characterized by pale–green, yellowish to brownish areas of irregular size and shape (oval to cylindrical) on infected leek leaves. Masses of spores are produced on the surface of the leaves, which turn from transparent to greyish, and then rapidly become a violet colour. Leaves become girdled in the region where mildew develops and the leaves collapse, resulting in dead leaf tips. The dead leaf tissue is often colonized by purple blotch, which is dark in color and obscures the downy mildew.

Downy mildew seldom kills leeks, but the leek growth may be reduced.

The relatively cool, moist weather that the UK has been experiencing favours the development of downy mildew in leeks.

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