Every year, I am asked if the peaches and nectarines that I sell are grown organically. The answer is no. We cannot grow stone fruit crops such as peaches, plums, nectarines and cherries without having to use both insecticides and fungicides. All of these crops are extremely susceptible to brown rot, rusts and insect damage from beetles, curculio, aphids, mites, stink bugs, borers, etc.
At present there are no organic or biological controls for the insects that attack these crops.
Many potential growers have attempted to grow these crops without having to use pesticides. None to date has been successful east of the Mississippi.
Sulfur can be used to a limited extent to help control brown rot and rusts, but our high summer temperatures and humidity allow only limited control, and the fruit cannot be stored without substantial spoilage.
Peaches, nectarines, plums and cherries can be grown without the fungicides in Arizona. But that is changing as the population increases and more and more people establish landscapes that need to be irrigated. Humidity is now becoming a problem in orchards.
Insecticides must be used even in Arizona to control the same insects that we are bothered with.
Both insecticides and fungicides have limited activity known as half-lives. The pesticides used today have much shorter half-lives than pesticides of past years. That’s why peaches, nectarines, plums and cherries have to be sprayed every 10 to 14 days from the time the flowers petals fall until they are ready for harvest.
As the harvesting season approaches, the insecticides that can be used are limited to just a few with half-lives of only a few days. Because these crops are highly perishable, only a few fungicides can be applied just prior to harvest.
Don’t Squeeze the Peaches!
Commercial growers are very aware of pesticide residues and strive to produce quality fruit that can be safely stored and marketed. But obstacles rise at both ends of the chain.
I learned from the produce manager of a large grocery chain that 20 to 30 percent of the peaches, nectarines, plums and cherries that are displayed have to be discarded daily due to two factors: physical damage caused by patrons and decay caused by brown rot. Patrons squeeze and bruise the fruit, causing tissue damage that is rapidly invaded by brown rot-causing organisms
In other words, grocery stores do not make any money from the sale of stone fruits. You don’t squeeze the Charmin, and you should not squeeze the peaches.
Getting Squash to Harvest
Q We’ve always had success with great big zucchini/ squash plants. One day they’re beautiful; the next they are flat on the ground. I understand this is due to some sort of beetle that eats the stems. We’ve been using Sevin pesticide on our garden, but it doesn’t stop them, so it seems.
–Peter Brooks, Chesapeake Beach
A With regards to your zucchini squash, stem borers are a big problem. One method I use is to spread a liberal amount of wood ashes around the plant just before they begin to sprawl on the ground. I also spray the stems and vines weekly with Sevin, making certain that the spray is directed inside the plant and not on the foliage Spraying the foliage has no effect on the stem borer because it is attacking the stems and not the leaves.
It is also important not to let the zucchini dry out. I irrigate my squash patch every second or third day depending on the amount of rain we receive. I try to give each plant four to five gallons at each watering.