Sometimes a hose-end sprayer can reach that high.

Your comment, "...most of my crabapple trees look like the picture..." made me recall an incident where a dead branch caused by an active canker infection was removed in a nursery situation, and the pruner tool was not sterilized between cuts, spreading the canker and damaging many trees over time. If your trees are mostly of the same cultivar or perhaps are other succeptible cultivars the disease may have been spread by the pruning tool. hortster

There are all sorts of causes to bark splitting, usually a response to an environmental factor like frost/thaw, sun scald, even fluctuating weather/temperature conditions. Fruit trees - like the crab - have thin bark and are quite prone to splitting. Typically it is more of a cosmetic issue than a serious threat to the health of the tree and the tree is usually able to adapt to and seal/scar over the split with ease. Here is a link that might be useful: the 411 on bark splitting

I am going to assume you didn't know about Cedar Apple Rust before you planted the trees, but just for the benefit of others who might be wanting to plant apples or crabapples, the best advice is to think long and hard before you do it. Because cedar trees are widespread in our state and very invasive, it is very hard, if not almost impossible, to grow healthy apples and crabapples here. I love apples, but have lived here for 10 years and never planted one because I don't want to deal with cedar apple rust. Since you've already planted the trees, though, you have to deal with it. So, in answer to your questions: I don't think it is possible to control it on the cedars themselves. What you can do is remove the cedar apples (the fungal growths, also known as galls) before they form horns. If they have already formed horns it is too late. And, if there are cedar trees within about 2 miles of you, the disease can be carried through the air, so removing the cedar apples from the infected cedar trees near you may help a little, but it won't prevent airborne cedar apple disease spores from infecting your plants. You can spray your crabapples with a fungicide that is labeled for use on crabapples for the prevention/control of cedar apple rust, but the spraying has to be done at very specific temperatures and at very precise times. I believe the spores transfer most readily when temperatures are in the 60s. The fungicide most readily available to homeowners for Cedar Apple Rust on crabapples is cholorothalonil, most often sold as Daconil, and often used by vegetable gardeners, for example, to prevent Early Blight on tomatoes. I think you also can use a different fungicide called Bayleton. Just read and follow the label directions IF it is not too late, weatherwise and temperaturewise, in your area. Even though your crabapple trees are new to you, they actually are several years old by the time you buy them, so the application of a fungicide following label directions should not harm them at all. Just be sure you dilute the fungicide and apply it as directed. The entire life cycle of cedar apple rust from cedar tree to its transferrence to apple trees takes almost 2 years. It is an ever-present threat. It is the reason you don't see vast orchards of apples in Oklahoma. Of the two crabapples you plante, I think Prairiefire is considered highly disease-resistant and Profusion less so. However, disease-resistant only means the tree has some resistance, not immunity, and even disease-resistant trees can and do get diseases. Cedar Apple Rust is the main cause of rust on apple trees, but you also have to watch out for the closely related Cedar-Quince Rust and Cedar-Hawthorne Rust. They are controlled/prevented by the same fungicides. Please understand though that even the regular application of fungicide is no guarantee the trees won't become infected. Understand also that cedar apple rust is not something that will be a problem only once. If is an issue for your trees one year, it probably will be an issue for them every year when the temperatures are in the precise range that allows the spores to transfer and infect apple trees. Only you can decide if you want to deal with the cedar-apple rust disease every year, or if you'd rather cut your losses and replace your crabapple trees with some other kind of tree that is more disease-resistant. Good luck, Dawn Here is a link that might be useful: Info on Cedar Apple Rust