Question
I have 2 large 4 yr old yukka plants in my front garden.
I recently treated my lawn for fungus.
2 days later I noticed tiny black & red insects all over the plant leaves. Is this related & how do I treat this
problem

Answer
No---it is not realted to the fungicide treatment.  As a plant pathologist, I can not identify the black and red bugs.  However, I can tell you that a week ago I had those same critters on my yuccas.  Hundreds of them.  I sprayed mine with an insecticide and they went away.  I would use malathion or sevin and drench the plant pretty good.  They are some kind of beetle and you may even notice kind of a sweet smell when you get close to them.  I dont know if they were hurting the plant or not, but I got rid of them with the insecticide.  I hope this helps solve your problem.  Thanks.