Looks like dollar spot to me. Symptoms/Signs: Small (1-3 inches diameter), brown to straw-colored patches of dead grass will develop. Irregular, light tan lesions with distinct brown borders will be present on the leaves at the outside edge of the patch. The small individual patches do not expand in size, but as the number of patches increase, they may merge together to form larger patches. White, cottony mycelia may be observed in early morning hours when dew is present. Below is a great link for Florida Lawns, You'll want to bookmark this one. LOOK in the disease management sections for pics and control of Dollar Spot, Gray Leaf Spot, and Cercospora Leaf Spot. All of these have similar characteristics, but different control options, so be sure you know which disease you have before any treatment. Your best bet would be to take a few of the effected blades and roots to your local extension office and have them diagnose your problem for FREE. Here is a link that might be useful: University of FLORIDA

That looks physiological to me, not pathogenic. There are a couple of possibilities, depending on what you do with your plants. Some nutrient deficiencies can look like that; magnesium, potassium, maybe molybdenum. If you haven't fed them recently, or if you have been feeding them a straight NPK food and your soil isn't the best, consider supplementing with a complete fertilizer or tonic, one which has trace minerals. (I'm fond of Superthrive for hard-to-pinpoint problems like this.) Low pH can also mimic nutrient deficiency. It could be fertilizer burn, though it's not perfectly typical. If you've been feeding them a lot, lay off for a bit and see whether it resolves. The last possibility I can think of is spray burn. Sulfur and some oils can burn foliage at high temperatures (over 85F) and even simple soap at high concentration can burn; it's common for the tips of the leaves to get higher concentrations of the spray as it runs off. You didn't mention any earlier sprays, but if you have done any, watch your temperatures and try to get an even spray without a lot of runoff. Don't mix different sprays together, either. I don't suspect a fungus because the yellowing pattern is so regular, and the dead patches are in the center of the yellow areas which speaks of it either being the center of the toxicity/deficiency, or being a victim of sunburn as the leaves get too pale to handle the sun. I hope some of that helps. :) --Alison

Orchid leaf

I don't see the orange either. I do see the brown spots which are quite indicative of Rust appearing on the bottom sides of the leaves. I have generally had good success with Neem oil. I buy the concentrate at 70% solution and mix 1 oz per gallon. Off the top of my head that would be a bit higher than the .5% concentration you stated but not decisively higher. If its older damaged leaves falling off and I still had rust I would continue treatments using all recommended precautions (not doing it in full sun, etc.) until the rust was gone.