A disease to the leaves causing them turn brown from the edges and eventually dying. Some leaves turning like a mesh before falling off. There are lot of big black ants along with tiny pest (looks like a miniature fly but crawls) roaming these trees. This is happening to all plants (avenue tree saplings) on the farm including Sunn Hemp which is just coming up (about 3 to 5 inches high). There were lot of weeds on the farm since rains started but about 3 weeks ago Sunn Hemp was sowed and rotovated the entire land. Photos are attached for clarity.
I am trying to save about 250 tree saplings that were planted 3 months ago. For 90% of tree saplings roots were established and new leaves are coming but they are being destroyed by this desease. Nursery who provided the trees recommended applying combination of celecron and blightex to the tree in addition to sprinkling gamaxin at the base. I would like to know if there are alternatives to pesticides to control this desease so trees can be established.
I’d appreciate any help understanding the issue and potential remedy to fix it.