Trichoderma will only attack the area where the leaf curl is on the leaf, the remaining leaf section remains intact and continues to grow and photosynthesis in the normal manner. Regular applications of Trichoderma can eliminate leaf curl completely. Trichoderma should be applied at leaf burst and then 2 or 3 times through the season. However as a living organic substance Trichoderma cannot be applied in conjunction with chemical applications.
Trichoderma also works on other fungal problems like Apple Scab (black spot), rust on Silver Beet and Celery, Powdery Mildew on Grapes and Cucurbits. However in these cases it works better to treat the plants before the fungus is apparent.
trichoderma will work well by spraying at leaf break and then a little later - you can also apply to the roots
unfortunatelyin Australia and Melbourne where I am based, it seems the only way you can get it is in commercial quantities - which is about $200 a kilo and covers about 500 hectares - I usually band together wit a few neighbors and we split it up - so maybe you have some friends or a garden group who might be interested in this.
it will last for a few years if you keep it in a cool place - I have also found it is good to heal tree wounds as it stops fungal attack. It cones as a slightly sticky brown lump - you break off about 1-2 table spoons then mix with 10-15 liters of water - I mix it up and leave it for a day which activates it - then apply as a spray - I alaso water it down ans pour around all my tree roots as well
because it is a natural micro organism you can use it safely on every thing it also works for strawberries and veges
now they mix it with a range of other beneficial organisms I have attached the info data sheet which has the address of the supplier
Good luck and happy gardening