more of my iffy orchids. virus, bacterial, fungal?

[Weetamoo]

[zainal abidin]

Very difficult to diagnose anyway need to remove the infected leaves and spraying with fungicide/insecticide if possible isolate.

[raybark]

Tell us about your water source and feeding regimen.

Some of those photos look like past damage that will not likely progress, but others look more nutritionally-based to me.

[Weetamoo]

Hi Ray,

I've been using r/o water. In sunny weather My new greenhouse gets quite hot and the humidity drops to around 25 -30%. I've been watering 2-3 times a week when its very hot and not watering when its cloudy or cold. I fertilize 2 times a month 1/2 t per gal K-lite. Occasionally some KLN or Kelp max. I'm trying to get more organized and consistant, and I'm trying to water a little less.

[raybark]

Clara,

1/2 tsp/gal is about 100 ppm N, which is my recommendation for weekly feeding, so I suspect a nutritional deficiency is part of the issue. The next time you water, do so with water containing a tablespoon of Epsom Salts per gallon to give your plants a magnesium boost. After that, up your feeding frequency to weekly, as that’s better than doubling the concentration at your current frequency.

Water is the driving force for growth, so it pays to adjust your potting media to accommodate that and water more often, not less.

If you do the calculations based up the pertinent chemical reactions, in order for a plant (any plant) to add one pound of mass (a few weeks for corn in mid-summer, a couple of years for a cattleya, 4 or 5 for a paph, or a lifetime for a tiny pleurothallid-type) the plant must absorb and process 200 pounds of water (~25 gallons), but only 5 grams (~1 teaspoon) of fertilizer nutrients.

Drop the KLN. It is stimulating root growth, which stimulates plant growth, but that, coupled with a nutrient deficiency, becomes a “double-whammy”. Besides, there is no better stimulant than KelpMax, and it provides a wide array of nutrients that fertilizers don’t. It should be used monthly @ 1 tablespoon/gallon.

I’ll also add that it pays to try to avoid wetting the plants when you water. I know it can be difficult - my greenhouse is PA was watered using an overhead “rain” system - so it pays to water early in the day so the plants have lots of time to dry before nightfall.

[Weetamoo]

Thank you for the guidance Ray! I've been a little confused as to how much to fertilize. I've seen recommendations to limit fertilization in the winter. I'll start with your recommendations. Thank you, and my hungry orchids thank you. Clara