New buds in brown color

My first year Flavor Grenade Pluot tree grows well, but recently it has a brown color tip. See picture please:

It is watered regularly. Here is in Austin, TX. Although the recent temperature is as high as 97F (33C), I think the brown color tip is not the result of sun burn because it is still soft. Because some of my persimmon trees were bitten by unknown pests, I applied (GardenTech’s Sevin 5% dust) once to all the fruit trees, including the flavor grenade pluot.

Could you please tell me what is it?


My bet is flagging from oriental fruit moth. Likely still in the shoot.

Piblarg, thank you for the reply.
Today, it is found a larger leave falls off. I don’t see any bug around there. Here are 2 pictures of its two sides:

Can you please tell me what is wrong?