What you described about the multiple branches radiating around the trunk, just below where the trunk has been top cut, is a typical growth pattern for such drastic top pruning. All too often growers have already done such pruning to larger crape myrtles when they are shipped to the retail nurseries. Did your area get the recent days' hard freeze around the Easter holiday? If so the CM in question might have a lot of dead wood which needs to be pruned out. If such a freeze happened, watch the tree as its remaining buds leaf out again. Once the tree appears to be fully leafing out enough to look recovered from any winter or freeze damage; totally remove any trunks or branches which fail to releaf. Also from the trunks nearest your house, completely remove all the way to the trunk any branches in the canopy which you can clearly tell will grow to infringe on your roof. Throughout the following growing seasons feed the tree with slow release quality food, and after every week which fails to provide an inch of rain for the shrub, suppliment the tree with that much water. Over the summer let the tree bloom naturally, and do not prune off the resulting seeds in an effort to extend your bloom season to the first freeze of late fall or early winter. By letting the tree bloom by itself and by being patient if it seems to slow down in bloom presentation after the first bloom flush; the tree will be enabled to put forth effort into thickening its branches and developing its proper rooting perportions. After the tree goes dormant, depending on when temps drop low enough for that, consider the space which any branching from the trunks still invade your roof line. cut, at that time, each trunk, all the way down to the root ball, whose canopy clearly will grow to infringe on your roof line. Hopefully when you have accomplished all the above pruning you will end up with the best of either a one or three main leader trunks. Then, in early march of the next year, prune out again all brittle dead wood, brake off the remaining seed pods and their twigs. Then turn your focus onto any remaining radiating branches which are growing just beneath the previously described, chopped off trunks. Preserve only a flexible and clearly healthy branch which grows the most directly upward and toward the direction where you want the trunk to continue growing. Prune away any other branches which are growing around the trunk near the same level of the healthy upward growing branch you selected to retain. To repeat: the one branch you choose to keep growing off the end of such chopped off trunks should be the one out of the ratiating bunches which appeares to be growing most upright, and growing in the right direction for the retained branch to assume the role of developing into a continuation of the trunk. Hopefully each single branch you select to continue the remaining trunks are thick enough to survive the following winter freezes. If not you will need to wrap each and their tunks with cotton insulator wrap prior to each freeze. If the temps are forecast to drop down to a hard freeze than add bubble wrap around the cotton wrap. Just be sure to remove the plastic bubble wrap any time the temps rise back up above 33 F. degrees. The above advised action takes a lot of dilligent effort, so if you do not think the tree is worth the trouble, simply remove it, grind the stump and main roots and purchase a 10 to 15 gallon sized, 25 to 30 feet potential height grower Crape Myrtle which has not also already been such drastically top pruned-down by the grower. With any such new CM tree you plant in the area, make certain to plant it far enough from the house to prevent roof damage, and to also prune train it properly each year just as you first described above.

First, yes, you spelled it right (the generally accepted way)! I have a hard time accepting the cold-kill argument (especially for the one with no foliage on the larger trunks). It's possible, but hard to accept since you are in such a warm area (zone 8b/9a). We only rarely have significant cold-related dieback (more than a few inches from the growing tips) on crape myrtles here in Tennessee, where it gets much colder. Have you noticed any other symptoms before the total dieback (signs of disease, pests, etc)? Has anything changed (unusual weather, chemical applications, etc)? Have you contacted your local agriculture extension office and asked them for ideas? They may actually be one of your best sources of information, since they should be familiar with your local conditions and be able to take a first-hand look.

Reluctantartist, The correct spelling of crape myrtle is with an "a". As ltruett's link indicates, this may not be the best choice for the style of tree you want, and you might be better off replacing it with one that has a more naturally vertical form. You could however do a lot to encourage your 'Acoma' to grow into a tree form. Proper pruning and maybe even staking the plant could result in a form more like what you seek. If you leave the plant alone, like you are doing now, I don't think you can expect it to take on the form you want. You should probably make a decision to either replace it or work with it and manage its form.

The seeds are in the hard pods. The pods are arranged like an orange, with several sections. When the pods start to crack, the seeds are ripe. You need to collect before the pods open completely or the seeds will fall out. The seeds look like papery commas and there are a lot in each pod. The seeds are very viable and easy to grow.