Cucumber problem

Hi - I'm a fairly new and inexperienced gardener. |I tried to grow cucumbers in the unheated greenhouse last year. The first lot disappeared ( I think they were too wet ); I grew some more and put them in the greenhouse - and the leaves all went paper-thin and fell off. I got no fruit at all, but that may be because they were quite late going in, in the end. This year ( ever-hopeful! ) I have put some more in the greenhouse. They are now about 18 inches high and some of the leaves towards the bottom of the plants have started to change again. They are going dry and pale brown/white, but the veins of the leaves are remaining bright green. Last year they were in big pots; this year I've put them in growbags. I'm keeping the soil moist, not wet. PLease please please can anyone help me - what am I doing wrong??????????

 

Stolen from another site, but might help


Problem: Cucumber mosaic
Affected Area: Leaf, Stem, and Fruit

Description: Vines are stunted, new leaves are dwarfed, mottled, distorted and may wilt and die. Fruit distorts and yellows early.

Control: Plant resistant varieties. Control aphids and cucumber beetles. Rotate placement from year to year.

Problem: Powdery mildew
Affected Area: Leaf

Description: White powdery substance on the leaves. Spores are transmitted by wind to healthy plants.

Control: Use surface or underground watering method to avoid wetting leaves. Plant resistant varieties. Change location from year to year. Fungicidal sprays are only moderately effective.

Problem: Alternaria Leaf Spot
Affected Area: Leaf

Description: Dry flecks surrounded by yellow halos appear on the leaves and enlarge into spots, which may group together to form nearly circular lesions. The lesions bear the black brown conidia of the pathogen. Severely infected leaves become yellow and senescent and then die.

Control: Satisfactory control can be achieved by reducing relative humidity in greenhouses, removing infected plant debris prior to crop establishment, and applying protectant fungicides.

Problem: Anthracnose
Affected Area: Leaf, Petiole, Stem, and Fruit

Description: On cucumber leaves, lesions usually first appear near veins, are roughly circular, range from light brown to reddish, and can reach more than 1 cm in diameter. The leaves may be distorted, and the centers of lesions may crack or drop out, creating a shot-hole appearance. On petioles and stems, lesions are shallow, elongated, tan areas. On fruit, lesions are circular, sunken, water-soaked areas which first develop as the fruit.

Control: Chemical control and resistant cultivars are the most effective controls of the disease.

Problem: Aphids
Affected Area: Leaf

Description: Aphids damage cucurbits by direct feeding, by contamination with excrement, and as vectors of plant pathogens and can occur just after the formation of the first true leaf.

Control: Insecticides are not effective in preventing the spread of aphid borne viruses, but may be helpful in control the onset of infection. Refer to current recommendations for registered insecticides.

Problem: Aster Yellows
Affected Area: Leaf, Flower, and Fruit

Description: Infected plants are easily detected by the conspicuous yellowing of young leaves, the proliferation of secondary shoots, and the rigid, erect habit of the plants. Leaves are often misshapen and smaller than normal and have stiff, thick laminae. Flowers are usually malformed and greenish yellow and often have prominent leafy bracts. Fruits are small, malformed, and lighter than normal color.

Control: Application of insecticide can drastically reduce leafhopper populations but is often ineffective in reducing the disease.

Problem: Bacterial Brown Spot
Affected Area: Fruit

Description: In honeydew melons, symptoms appear as conspicuous yellow brown, smooth, firm lesions up to 40 mm in diameter. Symptoms on melon are very similar with firm lesions that are slightly yellow brown, and up to 10 mm in diameter, extending 1-2 mm below the epidermis. Symptoms on melon fruit are obscured by the net.

Control: No control measures have been developed.

 

Keep the humidity up. Put some trays an inch or so deep near the plants and keep them filled with water. Gravel trays would do. i.e. provide a large surface area of water for evaporation.

Misting the plants will help too.

Leaves going yellow and crisp like paper / poppadoms can also be a sign of Red Spider Mite. They are quite hard to see with the naked eye, but should be visible on the undersides of the leaves. When the infection gets bad you will see their webs on the tips of the plant.

 

Sorry, but I can't imagine why you think that is acceptable. Providing a link would do just fine, and not infringe the other site's intellectual property:

GARDEN Cucumber - DISEASES, PESTS AND PROBLEMS

 

Well it was not stolen, as such and I did not want to post a link to another forum as it would have been advertising for them, so I copied some information that might have been useful and posted it here

 

Greenhouse cucumbers are tricky until the day and night temperatures become really warm, any chilling, it need only be one night, and the plants take a long time to recover.
The other point which I think might be relevant is that grow bags are difficult to water, especially since the quality of the medium, (compost) has gone down, and they dont hold water like they used to do.

 

Ah! it now all slots in place, so that is why they are now advertising growbags with gel crystals (and charging for it).

 

Thank you all for your advice - I will up the humidity and hope for the best. Can't see any red spider mites but will keep looking. Do I cut off the leaves that look all papery to let the plant concentrate on the better leaves or do I wait for them to get better now I'm misting etc??

 

I don't think the leaves will recover, so you might as well remove them