Here is Pseudomonas leaf spot on squash. With the cool, wet conditions we’ve had, this disease has been more common. UGA Extension Pathologist, Dr. David Langston, has reported seeing it already and had this to say:
“We are seeing Pseudomonas leaf spot on cucurbits again this year. The spots can appear dark and greasy at first, then they turn light tan in the center and you can see a concentric ring pattern in the lesion. I see a little bit every year, but not as much as we have seen the past two years. Usually the weather turns this disease around as warm (80o F+) dry conditions are unfavorable for the bacterium. There have been reports of this disease killing squash lately, and I saw that happen last spring as well. This problem has not been shown to defoliate watermelon, but it sure makes the leaves look bad.”
If growers feel the need to spray, the lowest labeled rate a copper brand on a 7 day schedule would help until the temperatures get warmer and stay warmer.
Wheat is flowering and kernels are starting to develop pushing into the milk stage. Most of the crop has been sprayed with a fungicide to protect from rust. April sprays should hold us out until harvest.
A few things to watch for:
Decatur County Agent, Justin Ballew, located wheat stem maggot in a field there. I have not seen or heard reports here. The maggot apparently bores into the stem at the bottom of the top internode and the grain head dies and turns white. UGA Extension Entomologist, Dr. David Buntin, says he has seen it before and usually at low levels in the field such as these. Below are two pictures from Seminole County Agent, Rome Ethredge.
For now we can still check for ahpids. Our threshold from heading to early dough stage is 10 aphids per head. Once the plant has lost its green color and we hit the hard dough stage, insect and disease management is ended. Aphids were not a problem in this field here, but I did see a hatch out. Something I’ve seen all season is good beneficial population. Here is a picture of a lady bug larvae (left) and some adult, baby, and mummy aphid on leaf (right).
I am getting reports of some flies pestering livestock, particularly horses and ponies. I took a picture of these flies on the microscope and sent them to UGA Extension Entomologist, Dr. Nancy Hinkle. She identified them as black flies (Simulium spp), also called “Buffalo Gnats.” Complains were these flies were biting in horses’ ears and causing them to bleed. The flies stay outside and did not move into the barn. Below is from Dr. Hinkle:
“These are black flies. They are native to Georgia and we have several different species. This one will die out when the weather warms, but we’ll have another resurgence of a different species in the fall. They love to feed in horses’ ears and will leave them bloody and scabby. They’re being produced in flowing streams, probably half a mile away from where the horses are (or more). Area control is possible with Bti, but that’s a governmental decision, not something the individual horse owner can undertake.
During the times of year when they were worst, you can slather the inside of our horses’ ears with petroleum jelly – a physical barrier. Otherwise, you have to spray the animal almost daily. As she observed, these flies will not enter structures, so keeping animals stabled during the day really helps.”
Folks have complained about flies bothering people, which they can also. Here is some information on black flies by University of Florida with some management options: http://entnemdept.ifas.ufl.edu/creatures/livestock/bfly.htm
Because weather conditions have impacted growers’ ability to plant, it has largely been the corn crop that has been affected. Though seedling disease are generally not a problem in field corn, cooler and wetter is the perfect recipe for fungal disease on any crop early. At this point, there is little that can be done for the corn, except pray for warm weather and sunshine which are in the forecast for the next few days. Below is an update from UGA Extension Pathologist, Dr. Bob Kemerait:
A) Regardless of crop or fungicide treatment, all growers are advised to delay planting until conditions are favorable for a rapid germination of the seed and vigorous early-season growth.
B ) In addition to increasing the risk to seedling disease, our abundant rainfall thus far in 2014 has also interfered with the opportunity to use a nematicide like Telone II. Most effective use of this fumigant requires that soil conditions be such that the moisture is neither excessive or too dry. Some growers already had to forego use of Telone or delay application.
C) Although Telone II can be applied “at-planting time” to cotton in Georgia, this should only be attempted when soil conditions are perfect for fumigation and the forecast is free of impending storms over the following 4-5 days after planting. Because of abundant rainfall in 2014, growers should exercise EXTREME caution before attempting at-plant applications of Telone in 2014.
D) Peanut growers are considering the use of Proline and Abound either in-furrow or as early season banded applications. Please remember the following:
- Early-season white mold is most often a concern when conditions are warmer than normal at planting and for the first 30-45 days after planting.
- CBR (Cylindrocladium black rot) is more of an issue when conditions are cooler and wetter at planting.
- IN-furrow use of Abound is a good supplemental treatment for seedling diseases, but has less affect on white mold or CBR.
- IN-furrow use of Proline has impact on CBR and some limited benefit for early season white mold.
- The optimum management strategy for early-season white mold occurs when Proline or Abound is banded over the peanut rows approximately 3-5 weeks after planting. Again, this is most critical in warmer years.
(The mention of trade names in this newsletter does not imply endorsement by the Georgia Extension Service, nor criticism of similar ones not mentioned.)
Growers tried to get in the field some today and it is still almost too wet. Corn planted early is progressing and we’ve had our herbicide sprays. We’re seeing skippy stands in corn as result of rain. This is a common sight in many fields and we’ve had to do some replanting. In many places, seed under water too long rotted and didn’t germinate. In other places, the seed withstood wet conditions and emerged later. In this case, corn is anywhere from two leaves to V5 growth stage.
There is some interest in pruning pecans with a large hedging machine (hedging). The goal of hedging is to control tree size and make it easier to control scab increasing spray coverage and light in the orchard while maintaining a high tree density. UGA Extension Pecan Horticulturalist, Dr. Lenny Wells, has this to say:
This is normally done in the winter and removes all the growth on one or both sides of a tree within a certain distance from the trunk and also usually tops the tree to control tree size. This is a common practice in the U.S. West and is beginning to be used here in Georgia.
- One method of hedging is to hedge one side of both rows on every other middle in two successive years (alternating rows), skip year 3 and begin again in year 4.
- Another method is to hedge every 5th row and over the course of 5 years, you hedge the whole orchard without taking too much growth at one time.
Preliminary research results here in Georgia indicate an increasing advantage to hedging as more of the fruit are within reach of more efficacious fungicide coverage, along with no negative effect on yield and usually a positive effect.
It’ll be another few days before we can get back into fields. Rainfall recorded at the Georgia Weather Station in Dixie showed almost 3 more inches of rain over the weekend. Caleb Clements with the UGA Extension Pathology lab came down to see where we had corn sentinel plots planted. This field has washed pretty bad in some areas. Caleb will be coming through this season checking for southern rust.
This field was planted Saturday, April 12th and was rained on shortly after planting. Caleb checked seed from the sentinel plots. If we were not able to get corn planted in early March, many growers haven’t been able to get back in fields to plant.
Filed under Corn, Disease