|What causes my Zucchinni & Yellow squash to wilt & die during 100 degree days and I am drip irrigating each 6 hrs for 15 mins? I also tried 24 hrs for 30 mins with the same results. I noticed the squash base stem gets yellow, decays when I first see the wilt. After a few days the plant dies. Note my Tomatoes, Cantelope, Peas, Peppers,Okra and more do not do this.|
|A few possibilities come to mind. It could be a problem with bacterial wilt or borers. Wilt is spread by cucumber beetles, so controlling them will go a long way toward helping the problem. To stop them, cover the plants with a summer weight row cover which will exclude them. Unfortunately, this means you will need to hand pollinate or open the cover occasionally for pollination to occur.
Borers tunnel into the vine usually near the base and you can actually see the hole or might notice the "sawdust" on the ground near the hole. These can be carefully removed from the vine using a sharp knife to make a slit where the borer is. Then bury portions of the vine at the nodes to try to cause it to add more roots so it can support itself and recover despite the damage.
Additional steps would be to clean up and discard all plant debris in fall and as it occurs during the summer, turn over the soil in fall and spring to expose any overwintering pests to the weather, and be absolutely sure to rotate your crops so that melons, squash, pumpkin, cucmber and gourds are not grown in the same location more often than at least every three years. In the event it was not bacterial wilt or borers, but another problem, the same prevention measures would apply with the exception of the row cover.
Another possibility is ineffective watering. If wilting occurs late in the day, don't automatically apply more water. Evaporation from the large leaves may be faster than the plant's ability to absorb and replace water, causing wilted foliage even though there is plenty of soil moisture. Pouring on more water, a natural reflex when we see wilted foliage, promotes root rot because saturated soil eliminates oxygen, which plant roots need to thrive. Wait until the next morning; if foliage is no longer wilted and the top layer of soil feels moist, watering isn't needed. Add a fresh layer of organic mulch to the bed to help maintain moisture. When you do apply water, make sure it soaks deeply through the root system, about 12 inches deep. Frequent, short periods of drip irrigation are not recommended because it allows salts to build up in the root zone. Always water deeply, but as infrequently as possible. Hope this info helps!