Dr. Clive Bock, USDA-ARS talked to attendees about pecan scab management at the 2018 Pecan Field Day
This year’s UF/IFAS Florida Pecan Field Day took place on Thursday, September 13, 2018 at the Jefferson County Extension Office in Monticello, Florida. Extension specialists from Florida and Georgia provided growers from across the state with information about current pecan production practices and management tips. Pesticide continuing education units (CEUs) were provided for Florida and Georgia pesticide applicators, as well as for Certified Crop Advisors. Simpson Nurseries of Monticello sponsored a barbecue lunch for the attendees.
The focus of the Pecan Field Day was primarily on production practices. Speaker topics included Best Management Practices (BMPs) and cost-share opportunities for growers, weed management, fertility, pecan scab management, insect pest management and information regarding new pecan varieties. The following provides a short summary of topics discussed by each speaker, followed by links to download PDF (printable) versions of the presentations given at the Pecan Field Day.
BMAPs, BMPs and Cost-Share Opportunities
Dr. Andrea Albertin, UF/IFAS Water Resources Agent provided information on the implications of the 2016 Florida Water Bill. According to this bill, farmers in a Basin Management Action Plan (BMAP) can choose to either: (1) enroll in the Florida Department of Agriculture and Consumer Sciences (FDACS) (BMP) program and implement BMPs or (2) monitor water quality on their farm. Currently, in the Florida Panhandle there are several BMAP areas: Wakulla Springs, Wacissa Springs, Jackson Blue Springs and the Suwannee River Basin. There is financial assistance available from FDACS, NRCS, water management districts, and the Mobile Irrigation Lab for farmers enrolled in the BMP program.
Herbicides for Pecan Orchards
Dr. Peter Dittmar, UF/IFAS Weed Specialist shared information on the current herbicides labeled for use in Florida pecan production. It’s important to know which weed you are targeting and selecting the proper herbicide for its control. He also discussed the benefits of using a pre-emergent herbicide to reduce the use of post-emergent herbicides and to decrease the likelihood of building herbicide resistant weed populations.
Dr. Lenny Wells, UGA Pecan Specialist discussed the importance of proper fertilization for young and mature pecan trees. Leaf sampling between July 7th and August 7th are the most effective means of determining nutrient requirements, and soil sampling should be done in the fall/winter to determine pH and toxicities.
Pecan Scab Management
Dr. Clive Bock, USDA-ARS-SEFTNRL Plant Pathologist spoke on the proper fungicide spray distribution and coverage for effectively managing pecan scab. He stressed the importance of rotating fungicide modes of action as resistance is an issue. Phosphite fungicides are effective for controlling pecan scab on the fruit and the foliage. There are organic options available for managing pecan scab.
Management of Common and Occasional Pests of Pecan
Dr. Ted Cottrell, USDA-ARS-SEFTNRL Entomologist discussed managing the black peach aphid using gibberellic acid, a plant growth regulator. He also talked about mating disruption as a possible control for the pecan nut casebearer and the hickory shuckworm. Mating disruption prevents the male insect from finding the female, thus the mating process is disrupted. There are several types of scale insects that occur on pecan, and timing insecticide applications to the crawler stage are effective.
New Pecan Variety Releases
Dr. Patrick Conner, UGA Pecan breeder provided variety data from trials in Georgia demonstrating trends in pecan performance. The pest resistance, yield, nut quality and tree attributes for several varieties were discussed. He also discussed tree availability for different varieties.
Sponsors of the 2018 Florida Pecan Field Day included Farm Credit of Northwest Florida, Savage Equipment of Georgia and Simpson Nurseries.
Florida Pecan Growers Association
Following the Pecan Field Day, the Florida Pecan Growers Association met for their annual meeting. The Florida Pecan Growers Association is looking to grow their organization and connect with pecan producers across the state. If you are a current or prospective pecan grower in Florida and are interested in becoming a member of the Florida Pecan Growers Association, please contact me. The Florida Pecan Growers Association will hold their next meeting at 9:30 EDT on March 1, 2019 at the Jefferson County Extension Office (2729 W. Washington Hwy. Monticello, FL 32344).
For more information on pecan production or about upcoming educational events, contact your local extension office.
Russ Mizell and Xavior Martini, UF/IFAS Entomologists, NFREC, Quincy
Citrus production in North Florida is expanding rapidly in response to the devastation of citrus in Central and South Florida due to citrus greening disease. Citrus acreage in southern Georgia is also increasing. Florida’s climate is situated in the temperate (North) and subtropical (Central and South Florida) regions. Thus, non-native pests from other similar habitats around the world can and frequently do become established in Florida. For example, some non-native pests of citrus that are well established in subtropical Florida include Diaprepes abbreviatus, better known as the “Apopka weevil,” the sugarcane rootstook borer, and the Sri Lanka weevil, Myllocerus undatus. Both of these weevils feed on citrus leaves as adults and their immature stages feed on the roots. Both species also feed on a wide range of other plant species damaging leaves and roots.
The annual low temperatures observed in North Florida the last few years have been higher, possibly due to climate change, and as a result have enabled some pests usually restricted to the subtropical areas of Florida to expand their ranges into the North Florida temperate zone. In addition, expansion of citrus culture with the corollary acceleration of plant movements across the state increase the risk of pest introduction from southern parts of Florida.
Via this article, we are alerting extension personnel, home gardeners, and more specifically citrus growers and nurserymen that the Apoka weevil, Diaprepes abbreviatus has been detected for the first time in an established population in Jefferson County, FL. The Apopka weevil was found in a nursery in Jefferson County, and has not been found in citrus in North Florida to date. The Apopka weevil has several hundred known host plants including citrus, sugarcane, vegetables, fruits and many woody landscape plants. Sicklepod, Senna obtusifolia, and pokeweed, Phytolacca americana, appear to be favorite adult hosts in North Florida in August-September. The large black and white-striped and often orange colored adults (Fig. 1 – C and 1D) feed on fresh leaves where they place their white egg masses in pouches (Fig. 1 – A) made from 2 leaves connected together. The larvae (Fig. 1- B) hatch and fall to the ground where they feed on plant roots often at depths of 1-2 feet or more. There are 2 generations per year in southern Florida, but the number and timing of those that will occur in north Florida remains unknown. Adult weevils are easily detected, and often occur as mating pairs. They are not known to be great fliers; however, the larvae can be found in, and be spread around while infesting plant roots in containers.
Fig. 1: Diaprepes abbreviatus (A) eggs (B) larva, (C) orange form adult, and (D) white form adult. Picture by Tai Huang (A) and Lyle Buss (B, C and D).
This weevil is a quarantined pest, so nurseries in infested counties are required to follow specific insecticide treatments prior to shipping outside of the quarantine area. Producers of any potentially infested crops should monitor visually for the adult weevils by looking for feeding damage and adult weevils on the crop and associated weeds.
Further information on this insect pest can be found in the following UF/IFAS publication: Diaprepes Root Weevil, Diaprepes abbreviatus.
A few weeks ago I was lucky enough to attend North Carolina State’s Tomato Field Day, at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC. Every summer crowds flock from all over the Southeast to learn what’s new in the world of tomatoes. Since it’s not always convenient for you to drop what you’re doing to make a road trip to North Carolina, I’ll highlight something I learned from the field day.
Stink Bug Control by Dr. Jim Walgenbach
The brown marmorated stink bug (BMSB) was introduced into the United States from Asia. The insect pest was first found in Pennsylvania and is suspected to have made its way to the US in packing material. BMSB was first reported in 2009 in Hillsborough County, FL and since been found in additional Florida counties. It has a wide host range including fruits, vegetables, and ornamentals.
Fifth instar nymph of the brown marmorated stink bug on raspberry in Allentown, Pennsylvania. Photo Credit: Gary Bernon, USDA-APHIS
BMSB has a typical stink bug body shape and size with a mottled brown coloring. The key identification feature is alternating dark and light bands on the last two antennal segments.
Trissolcus japonicus adults. Female to the left; male to the right. Photo Credit: FDACS – DPI
Biological Control with Natural Enemies
Dr. Walgenbach’s team is currently researching the impact of suppressing BMSB populations by native predators such as: katydids; jumping spiders; earwigs; and lady beetles. Current observations indicate only a minor effect from these predators on BMSB.
BMSB egg masses parasitized by T. japonicus. Photo Credit: Matt Lollar, University of Florida/IFAS Extension.
Trissolcus japonicus Assessment
A regional effort has been implemented to monitor the introduction, spread, and efficacy of the Asian parasitoid Trissolcus japonicus. Trissolcus japonicus is a tiny wasp that parasitizes the eggs of various stink bug species. It was first collected from China and brought back to quarantine facilities in the US for evaluation, as a potential biological control agent. Host-specific tests have indicated that T. japonicus prefers to parasitize BMSB eggs over eggs of other stink bug species. It is suspected that release permits for the wasp will be available from the USDA in the near future.
Reporting in Florida
The brown marmorated stink bug overwinters in homes to keep warm. If stink bugs are found in yuor home, they may be the BMSB and should be reported to the Florida Department of Agriculture and Consumer Services Division of Plant Industry. Specimens should be collected for identification.
To follow the research of Dr. Walgenbach and his colleagues, please visit NC State’s Entomology webpage.
Throughout my 22 year history as an Extension Agent, I have been the first responder for all sorts of strange things farmers, ranchers, and landowners encounter. This is one of the critical roles county agents play all over the country. If you see something odd or unusual, whether it is a new weed, insect or disease, your county agent should be one of the first people you contact to get information. It is very possible that if you find something you have never seen before, others may not have not seen it either. County agents are connected to a vast network of experts and identification labs that can help figure out what those strange new things are. Because of the ports, huge numbers of visitors, and tropical storms, new pests and diseases show up in Florida on a regular basis. It is very important to have new pests identified, before they have the opportunity to spread.
Most of the time the plants, bugs, and diseases agents have identified by experts are harmful in some way to the crops we grow. Whether it is toxic weeds in pastures, insects feeding on plants, or diseases in crops, the first thing you need to know is, “What is it?” Once the issue is identified, most of the time there are some type of control options available. Sometimes, however, things are not at all what you expect. Such was the case this summer as four types of plant pests were identified that turned out to be harmless, and in some cases were actually beneficial.
Aschersonia aleyrodis on Satsuma is a fungus that feeds on whitefly nymphs. Photo credit: Doug Mayo, UF/IFAS
A citrus grower thought that his satsuma trees were under serious attack. White flies were already an issue as noted by the sooty mold growing on the leaves, and then this terrible scale that he had never seen was all over the undersides of the leaves of the trees. While from a distance this looks much like a harmful scale insect, it turned out to be a beneficial fungus that destroys whitefly nymphs!
Dr. Xavier Martini, UF/IFAS Entomologist in Quincy shared the following information:
What you have is not scale, it is citrus whitefly nymphs that have been attacked by an entomopathogenic fungi called Aschersonia aleyrodis. It is very good to have this fungus, because it helps control the whitefly population.
You can read about this in the Featured Creature article entitled: Citrus Whitefly. Scroll down to the section called: Parasitic fungi for more details.
Aschersonia aleyrodis fungus on the underside of a satsuma leaf looks terrible, but it was actually making a bad situation better by reducing the whitefly population on young satsuma trees. Photo credit: Doug Mayo, UF/IFAS.
The beneficial fungus Beauveria bassiana is a natural enemy of kudzu bugs on soybeans. Photo credit: Doug Mayo, UF/IFAS.
A soybean grower saw something he had never noticed before. A white mold was growing in spots all over the stems of soybean plants in a field. This is where you have to be careful. Soybeans can get white mold, which is caused by the fungus Sclerotinia sclerotiorum. If you do a google search for Soybean white mold, you will find pictures that look somewhat similar. Upon closer inspection, at the NFREC Plant Pathology Lab, in Quincy, the fungus was actually Beauveria bassiana which is a biological control of kudzu bugs. The white spots in the photos are actually dead or dying kudzu bugs, and the fungus was growing on the insects, not the soybean stalks. You can read more about this beneficial fungus at: Kudzu bugs’ decline is attributed to two factors.
The white spots are beneficial fungus Beauveria bassiana that are attacking kudzu bugs not the soybean stalks. Photo credit: Doug Mayo, UF/IFAS
Slime mold found growing on a centipede lawn. Photo credit: Doug Mayo, UF/IFAS
A landowner noticed this really strange growth on her centipede lawn. It looks hideous and destructive. In truth, it was a relatively harmless plasmodial slime mold, named Fuligo septica.
Larry Williams, UF/IFAS Okaloosa Horticulture Agent shared the following information:
Slime molds mostly function as saprophytes, feeding on and breaking down organic matter. It should not cause any permanent problems or major damage to the lawn. One such slime mold is commonly referred to as “dog vomit” slime mold.
Here is a link to an article on slime molds that pop up on lawns, in mulch, and damp areas under trees with high organic matter: Those Mysterious Molds
Slime mold growing on the moist organic matter in a Jackson County Lawn. Photo credit: Doug Mayo, UF/IFAS.
Oklahoma State University’s diagnostic labs had gotten so may calls from concerned homeowners that they developed a YouTube video on slime molds:
Harmless slime mold growing on centipede lawn after multiple rainy days. Photo credit: Doug Mayo
A similar scenario was seen on a centipede lawn at a county building in Jackson County. This slime mold is commonly found on lawns and pasture grasses during extended rainy periods in Florida. While it looks like a serious disease, it is really just another plasmodium species that feeds on decaying organic matter. As with the large slime mold in specimen 3, what you are seeing is actually the spore masses that will generate more slime molds when conditions are favorable again for growth. You can knock these off with a garden hose, if you want to, but they disappear almost as fast as they form. No real harm is done to the grass that is just serving as a platform for slime mold reproduction.
Read more about it in this article written by Matt Orwatt, UF/IFAS Washington Horticulture Agent: Frequent Rains Induce Slime Mold in Panhandle Lawns
Most of the time, when you see something that does not look normal it is a bad thing, such as weeds, fungal diseases, or damaging insects. But before you spend money on a control, it is really important to have a positive identification of the pest. Not everything unusual is harmful. Modern pesticides have become very target specific, so it is vital to first find out what this new thing is before you spend money trying to control it. So the next time you see something alarming or strange in your crop, pasture, or landscape, contact your local county agent, so you can find out for certain what you are dealing with, and get some science-based advice on a plan of action, if one is needed.
What is conservation tillage?
Conservation tillage refers to soil cultivation with direct drilling (no tillage) and minimum tillage. Conservation tillage is often used in conjunction with cover crops to allow surface incorporation of crop residues. Conservation tillage maintains a minimum of 30% of the soil surface covered by residue after drilling. Oppositely, conventional systems of tillage leave less than 30% of crop residues, and often none, on the soil surface after crop establishment. Conservation tillage conserves soil moisture, reduces run-off, increases the surface soil organic matter, reduces soil erosion and water contamination. Conservation tillage has been promoted in the US because it provides substantial environmental benefits, including reduction of soil erosion. This has become more important with climate change that is exacerbating the problem of soil erosion with erratic rainfall events and greater frequency of storms.
What are the effects of conservation tillage on beneficial insects?
Conservation tillage along with cover crops helps promote year-round natural enemy populations by providing alternate prey, reproductive sites, and protection from adverse conditions. Conservation tillage increases grass weeds and retains organic matter, leading to an increase of detritus feeding species upon which beneficial predators depend.
Conservation tillage can also reduce the environmental impact of insecticides by modifying the soil structure and affecting the degradation of insecticides in the soil. The fate of insecticide following application depend of many factors including insecticide’s active ingredient and adjuvants, environmental conditions, and soil properties. Insecticides may cause severe or chronic effects on beneficial organisms before they are degraded into harmless compounds.
A recent study conducted in peanuts at the North Florida Research and Education Center in Quincy demonstrated that predators of soil pests were protected by conservation tillage. The experiment consisted in a peanut field planted after a cover crop of oats. The field was divided into areas with conservation or conventional tillage. The peanut field was then treated with different types of insecticides. Soil pests found in the peanut field included mole crickets, click beetles, and peanut burrowing bugs, whereas soil pest predators included earwigs and ground beetles. Both soil pests and predators increased significantly under conservation tillage (Fig. 1). However, the application of insecticides on conventional tillage, such as imidacloprid, decreased significantly the number of soil pests as well as the number of predators.
Fig. 1: Increased of natural enemies in peanut soil, under conservation tillage vs conventional tillage.
Interestingly, under conservation tillage the number of soil pests also decreased following insecticide application, but the predator populations remained at the same level as in the untreated area. The conclusion of this study was that conservation tillage increased significantly the number of soil pest predators and potentially protected them against the non-target effect of insecticides. Therefore, conservation of natural enemy population can be added to the numerous advantages of conservation tillage in peanuts.
For more information on this topic, use the following publication link:
Fall Webworm beginning to get started on a branch tip. Image credit: Matthew Orwat
Bare limb tips and clusters of webbing in pecan trees are often the first sign that fall is right around the corner.
This webbing is caused by clusters of the larvae of the Fall Webworm (Hyphantria cunea (Drury)) which is often also called Pecan Webworm. “Fall Webworm” is a bit of a misnomer in our region since they are able to strike in spring and summer thanks to our long growing season. They are most noticeable in the fall thanks to cumulative effects of earlier feeding.
The adult form of the fall webworm is a solid white or white and brown spotted moth that emerges in late March through August in southern climates. After mating they lay orderly clusters of green eggs, usually May through August. Soon after emergence, the larvae begin creating silk webs to protect themselves as they voraciously feed on their various host plants, of which Pecan is of primary agricultural importance in this region.
Although they are capable of defoliating complete trees, especially smaller ones, most seasons they are kept in check by beneficial insects such as the paper wasp. It is beneficial for small orchards or home growers to scout their trees from June through August. If small webs are observed in young trees, it is best to prune them out with a pole saw or pole pruner and dispose of the branch. Pruning of small branches does not harm the tree, but it may be of no benefit to remove small webs in larger trees, if they are being controlled by natural enemies.
Active feeding by webworm on pecan branch tip. Image credit: Matthew Orwat
Most large pecan orchards have a routine insecticide program, so fall webworm rarely creates problems. For smaller orchards or homeowners it is difficult to spray for control, due to the cost of the equipment required to get the spray into the tree canopy. If spraying is an option, many insecticides containing spinosad or Bacillus thuringiensis (Bt) exist. Both of these products target caterpillars while not harming beneficial insect predators that feed on these worm populations. Several more toxic insecticide products exist that will control fall webworm, but they often exacerbate insect problems by killing off beneficial insects that might be controlling other insect pests.
Fall webworm is not usually a serious problem for pecan production. Fortunately, when control is warranted, there are plenty of options available.
Leaves stripped by Fall Webworm. Image Credit: Matthew Orwat