Cathie,

Your photos of your peach tree leaves are very helpful.  They look to be infected with Peach Leaf Curl, a fungal disease common to peach trees. Earlier this spring, fungal spores that overwintered in bark crevices and buds infected leaf buds as they swelled until they fully emerged.  The spores on the leaves can then infect the forming fruit. So it's likely the fruit may already be infected. This causes early fruit drop or distorted fruit. The pyrethrin you applied would not have caused this leaf distortion.  It is used as an insecticide with no affect on a fungal disease.

Unfortunately there isn't anything you can do right now to treat the present infection.  However, you can take measures to prevent infection next spring.  Keep the tree healthy giving it 1 inch water/week when we're in a dry spell.  Cleaning up all infected leaves and fruit removing them from the area will reduce infecting fungal spores.  Also after all the leaves have fallen, spray the tree with a fungicide containing chlorothalonil or a copper based fungicide.  Follow the label's instructions.  These are 2 web sites that have further helpful Peach Leaf Curl information.

https://extension.psu.edu/disease-of-the-month-peach-leaf-curl

https://hort.extension.wisc.edu/articles/peach-leaf-curl/

As for the the splits in the bark, this may be  sunscald.  Peach trees are especially prone to this because of their thin bark.  It occurs during winter or early spring months when there are alternating warm temperatures followed by freezing. It's best not to paint or cover these split and letting the tree form it's own callus.  This web site has further sunscald info:

http://plantclinic.cornell.edu/factsheets/barksplitting.pdf

 When I magnified your photo of the bark I didn't see any gelatinous ooz from the base which would indicate a Bacterial Canker.  If there is gelatinous material from here please let me know.

I hope this information is helpful.

Jane

t occurs with when there are alternating warm then freezing temperatures during the winter