havent heard of that. but it wouldnt hurt to only water the soil when your trees are in bloom to prevent fungus or other stuff from affecting your blooms.

the inflo may take a while to grow and flower, but the blooms themselves only last a few days.

Yes it better to just water the tree at the base. a Mango tree will generally be more productive if during its flowering period , they are kept dry.

some varieties are more fussy about this than others.