Friday, May 29, 2015

SCA first found in sorghum fields in Northern Blacklands.,

  Northern Blacklands Report, May 29, 2015.

   Frequent and heavy rains during the past weeks have made many sorghum fields inaccessible to field scouting.  However, sugarcane aphids were found in very low numbers in the sorghum fields that could be scouted this past week in Hill and McLennan Counties.  Infestations average less than 1 SCA per leaf.  When found, only 1-3 scattered nymphs are present and very few colonies have been observed.  Also, very few beneficial insects are present.  The scattered nymphs and lack of colonies suggest the frequent rains this spring, often accompanied by strong winds, have knocked aphids from the plants.  This effect and cool temperatures have probably kept SCA numbers low to-date.  Sorghum is pre-boot, about 2-3 ft tall. Sugarcane aphids were found on 16% and 25% of the Johnsongrass tillers examined at two locations in McLennan County, but again SCA were typically present as scattered nymphs. Winged aphids are rare, representing less than 1% of all SCA observed.  Submitted by Allen Knutson and Marty Jungman.

Brief Update from The Coast; New Map Format

Dr. Robert Bowling, Extension Entomologist in Corpus Christi, makes the sugarcane aphid distribution maps. This year he is color coding the affected counties to reflect sugarcane aphid densities. Green indicates populations that are below the 50 aphids per leaf threshold, yellow indicates populations at threshold (50 - 125 per leaf), and red indicates large populations.


Dr. Bowling reports that SCA populations in south Texas have been much lighter than expected. This may be the result of heavy and persistent rain across large portions of Texas, but particularly south Texas. Natural enemies were present throughout the winter, and particularly lady beetles (adults and larvae, especially Scymnus lady beetle larvae) were observed among SCA at several overwintering sites. Parasitoids (one Braconid wasp but mainly Aphelinidae species) and predators like syrphid fly and lacewing larvae are abundant. Sorghum planting dates in south Texas are scattered all over the calendar. Some fields in the LRGV were planted near the end of January and the last fields were planted around the first of May. These late planted fields may be vulnerable to a wide range of pests; rice stink bug populations were very large in some wheat fields and remain active on various weed hosts. Fall armyworm populations are variable and trap collections, approximately 30 per week in the Corpus Christi area, suggest very low populations in south Texas at this time. Corn earworm, Helicoverpa zea, is practically non-existent right now (fewer than 10 moths per week over the past  4 weeks).  Sorghum midge is not much of an issue right now but has a high probability of being an issue in some of the late, late planted sorghum.

Dr. Bowling reports that SCA populations on sorghum along the Coastal Bend are starting to increase this week but populations remain very low as of this report.  Winged SCA have been found over the past three weeks but persistent rains may be hampering their ability to colonize fields.

Friday, May 22, 2015

Update on SCA in the Lower Rio Grande Valley : May 22, 2015


This week and last week I received reports of some fields being sprayed with high SCA populations mainly in the eastern Cameron reaching all the way north to the Willacy county line and in the mid Valley area in Hidalgo and Cameron counties.  However, in a lot of the LRGV grain sorghum fields we are finding SCA but in Very low numbers.  We have yet to reach the threshold of 100 SCA/leaf here at the station in Weslaco as we have had continuous SCA presence and presence of winged SCA; but natural predator populations have been seen keeping SCA numbers low below 20 per leaf or lower counts.  It is quite a difference from last year when here on the experimental fields in the AgriLife Center at Weslaco and some commercial fields in the RGV we had SCA populations of 700-2,000 per leaf.  Also this year environmental factors such as the continuous rainfall and overcast days we believe has also inhibited the SCA from reaching soaring populations. Last year we had rainfall but it was not continuous and we also had intense sunlight beaming down, while this year the rain has kept coming with overcast days and pleasant working weather conditions outside (aside from the muddy fields and mosquitos).  With that said I’d advise you to please check your fields before you spray.  Many have had the pressure to spray these last 3 weeks given the recent rainfall and potential for more rain, however I would strongly recommend that if you are not seeing an average SCA population of 100 SCA/leaf then you should wait if possible so as not to decrease the beneficial insects present keeping the SCA in check.  Please CONTINUE CHECKING your fields because it is possible a second outbreak of SCA around the harvest time as occurred last year. What we have been observing in the field is continuous predation from beneficials even as new winged aphids fly into fields and reproduce.

Tuesday, May 19, 2015

Sugarcane aphid scouting card available

A laminated Texas sugarcane aphid scouting card is now available through most Extension Agents - IPM and Extension Specialists. The cards are also being distributed at sugarcane aphid extension meetings and field days. The card provides ready reference for scouting techniques, thresholds and shows what approximate numbers of aphids look like on a leaf.

An electronic version of the card is available here.

This card is hot off the presses and we are working on a way for people to send a stamped, self addressed envelope to have one mailed to them.

The card has photos of sugarcane aphids but does not have information on differentiating it from other aphid species. That information is available here.


Tuesday, May 12, 2015

Sugarcane Aphids in North Texas

   Surveys of Johnsongrass this spring indicate the sugarcane aphid SCA may have overwintered this year in north central Texas.  This is contrary to the earlier assumption that SCA could not overwinter in regions where its host plants, Johnsongrass and sorghum, did not remain green.  Thus, it was thought that SCA infestations in this region resulted from winged aphids carried by the wind from south Texas. While winged migrants from the south may still be important in initiating infestations in north central Texas, there is now the possibility that overwintering (local) SCA may also play a role. A likely scenario is that SCA numbers in Johnsongrass will eventually increase this spring to numbers that generate winged forms which can then fly or be blown from Johnsongrass into nearby sorghum fields. 

This spring, SCA have been found in Johnsongrass as follows: 
April 9, Hill County, near Hillsboro, TX,   
April 14, McLennan County, near McGregor, TX,   
May 5,  Hunt County, near Greenville, TX,   
May 5, Fannin County,  near Bonham, TX  

     Numbers vary from 2-3 aphids to up to 30 per colony, and are more abundant at the southern site (McLennan County).  In the most northern site, Fannin County which is on the Oklahoma border, SCA were found on only 2 of 100 Johnsongrass stems examined. Thanks to Marty Jungman who helped with the survey in Hill County. 
    I assume these are overwintering SCA since it is too early in the spring to expect winged migrants from the south to have initiated these colonies and, except for one individual in a colony of 30, winged SCA aphids have not been observed at any of these sites. In addition to SCA, bird-cherry oat aphids, greenbugs, corn leaf aphids and yellow sugarcane aphids (the latter the most abundant), along with a very few aphid  mummies, were observed in these samples.  

  

Monday, May 11, 2015

Update: SCA in the LRGV 5-11-2015


This week we continue to see increasing populations of SCA. Some of the first commercial sorghum fields were sprayed for SCA as of last week continuing into this week. The presence of SCA seems to be in greater abundance closer to the coast in eastern Cameron County but is dispersing rapidly as more winged aphids have emerged. On another note we are starting to see some sorghum midge in some fields.  Try to avoid spraying pyrethroids to control sorghum midge that way you will not inadvertently flare SCA populations.  Although this spring is notoriously unpredictable for weather patterns and pest populations please continue monitoring your fields, we have observed abundant numbers of beneficial insects (lady bugs, lacewing, syrphid flies, parasitoids and even spiders) that might be holding SCA below levels that could cause damages and if you disrupt them we can produce SCA outbreaks.

Wednesday, May 6, 2015

2015 Sugarcane Aphid Management Guide Released

The 2015 Sugarcane Aphid Management Guide has just been released and can be found at: http://lubbock.tamu.edu/files/2015/05/SCA-Management-Guide.pdf .

This publication contains the latest information on biology, scouting, economic thresholds and insecticides for aphid control. The formal name of the publication is "Sugarcane Aphid: A New Pest of Grain and Forage Sorghum" and it has seven co-authors.

Video 4: Observations on insecticides for control of sugarcane aphid in 2015

We have just posted a 24-minute video presenting observations and discussion of insecticides for control of sugarcane aphid in the 2015 season. Seed treatments and foliar insecticides are discussed as well as best practices for insecticide use and optimal control.

Video 4: Observations on insecticides for control of sugarcane aphid in 2015.

Monday, May 4, 2015

Video 3: What to expect from biological control in suppressing 2015 sugarcane aphid populations

A five-minute video that discusses what kind of help to expect from biological control agents in suppression of sugarcane aphid populations, and why it is important to preserve biological control agents.

Video 3: Will biological control help control the sugarcane aphid?

Video 2: 2015 perspectives on what to expect from sorghum hybrids resistant to sugarcane aphids

The second video in the pre-season sugarcane aphid series features a roundtable discussion on what to expect from sorghum hybrids that are resistant to sugarcane aphid. There are many unknowns with respect to host plant resistance in sorghum and a conservative approach is advocated. The video runs 8 minutes and 35 seconds.

Video 2: 2015 perspectives on sorghum hybrids expressing resistance to sugarcane aphid.

Video 1: Starting the 2015 Texas Sugarcane Aphid Season

Texas AgriLife Extension Entomology personnel have prepared video units on the sugarcane aphid for the 2015 season. The first video discusses aphid arrival time, early detection, identification, biology, and the damage potential as related to infestation timing. This 32-minute video is applicable to the entire state of Texas.

Video 1
Topic and video timecode:
Historical spread (4:19)
2015 starting distribution (6:56)
Early detection is important (8:13)
Sampling for early detection (11:13)
Aphid identification (14:13)
Sugarcane aphid biology (19:28)
Potential damage based on infestation timing (25:11)

Future videos will follow over the next week.