Tomato yellow leaf curl virus (TYLCV) is a whitefly-spread virus that makes young tomato leaves curl upward, turn yellow at the edges and stay small, while plants stunt and drop flowers. There’s no cure: infected plants don’t recover, and early infections can wipe out fruit set. Prevention is the whole game: virus-free transplants, whitefly exclusion and control, resistant varieties, and prompt removal of infected plants.
Impatiens necrotic spot virus (INSV) is a thrips-spread virus that causes brown to dark brown spots and dead patches on lettuce leaves, often mistaken for fertilizer burn. There’s no cure. Infected lettuce is usually unmarketable, and young plants can stunt and die. Control depends on stopping western flower thrips, removing infected plants and managing weeds that harbor both the virus and the insect, a lesson from California’s Salinas Valley.
Tomato leaf mold is a fungal disease of greenhouse, high-tunnel and grow-room tomatoes caused by Passalora fulva . It starts as pale yellow spots on top of older leaves with olive-green, velvety mold underneath. University of Minnesota Extension says it’s driven by relative humidity above 85%. The fix is mostly climate: lower humidity, add airflow, keep leaves dry, remove infected leaves and grow resistant varieties.
Tomatoes not turning red are usually waiting on time or stuck in the wrong temperature. Purdue Extension notes red pigment doesn’t form above 86°F, and University of Missouri specialists say ripening is fastest at 68–77°F. Fruit also needs six to seven weeks from pollination to mature. Most green tomatoes ripen once temperatures are back in range. If you get yellow shoulders or blotches, check potassium and heat.
Springtails in hydroponics are usually a moisture signal, not a crop emergency. These tiny, jumping hexapods (about 1/16 to 1/8 inch long) feed mostly on fungi, algae and decaying organic matter. University extension specialists say they rarely harm established plants, though large numbers can nibble tender seedlings. If you see them, dry out wet surfaces, clean up algae and old roots, and they usually fade within days.
Shore flies are small, sturdy, dark flies with light spots on their wings that breed in algae and standing water. Fungus gnats are delicate, long-legged, weak fliers whose larvae live in moist media and can feed on roots. Extension entomologists say shore fly larvae eat algae, not plants, so the fix is algae and moisture control. Fungus gnats need drier media plus larval control. Correct ID saves time and money.
Mint rust is a fungal disease caused by Puccinia menthae . It shows up as pale, twisted spring shoots and dusty orange pustules under the leaves, later turning yellow and then black. It spreads through infected stems and rhizomes, so cutting leaves off rarely cures it. The reliable fix is to remove and bag infected plants, keep foliage dry, and restart from clean stock. Don’t eat or sell rust-spotted leaves.
Banana peel water for plants is mostly a myth. Banana peels do contain potassium, but University of Maryland Extension says it is “not aware of any research” showing that soaking peels makes fertilizer-strength water. A Clemson Extension director adds that nobody knows what, if anything, leaches into the jar. Compost the peels instead, and feed plants with a labeled fertilizer based on a soil test.
Aspirin for plants is based on real science but oversold online. Plants use salicylic acid (SA), the compound aspirin breaks down into, as a signal to switch on their own defenses. However, University of Minnesota Extension Master Gardeners found the evidence “very thin” that spraying aspirin helps tomatoes. The only replicated home-garden trial we found, at the University of Rhode Island, couldn’t test disease control because no disease occurred. Aspirin is not a disease cure.
Superthrive hydroponics use is popular, but the evidence is mixed. Superthrive’s label ingredients include vitamin B1 (thiamine), a small amount of the synthetic auxin NAA (1-naphthaleneacetic acid), nitrogen and kelp. Extension research says vitamin B1 alone does not stimulate root growth in whole plants, while auxins like NAA can affect rooting. If you try it, use the maker’s low rates (¼ tsp per gallon for seedlings and clones), keep your base nutrients unchanged, and judge it with a side-by-side test.