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Texas
Agricultural
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Boll Weevil Field Activity Increased Boll weevil trap numbers continued to decline this week. Counts in many traps were 0. Four traps were showing slightly less or more than 5 boll weevils per day per trap which would be more than 35 weevils per trap per week, a high value for this time of the year. The high trap counts were trap number 17-north of Edcouch, #63- west of Santa Rosa and #'s 101 and 102 south of San Benito. Boll weevil activity was found in a few, scattered fields, mostly in the irrigated areas. A minor number of punctured squares were reported from a couple of different locations in Hidalgo county this week. All of the in-field weevil activity was confined to the edges of the infested fields, as is usually the case in the early season in the LRGV. The new punctures probably point to the fact that the first generation of weevils has begun to emerge and start to feed and lay eggs in cotton. This is another reason to try to finish overwintering boll weevil sprays before the first of May. Since the first generation is emerging from punctured squares, it points out how important killing weevils early, before squares are large enough to lay eggs into can be. Also, first generation weevils typically begin to emerge about the end
of April every year here, so treating for overwintered weevils after the first generation adults have begun to emerge means the same thing as closing the barn door after the horse has escaped. It's just plain too late. Aphid Infestations on the Rise Aphids were showing signs of increasing in many area fields this week. No reported or observed infestation required treatment. Beneficial insects, particularly lady beetles and syrphid fly larvae were feeding heavily on the aphids. In some situations, more than 3 lady beetles (larvae and adults) per plant were observed this week. No signs of parasite activity were observed. Once parasite move onto an aphid colony, the majority of the aphids generally become short time survivors. All fields need to be monitored carefully for aphid and other pest infestations. Once cotton begins to bloom, as some has, the threshold for aphid infestations drops from 50 aphids per leaf to 25 or less per leaf. Aphids generally can do much more damage to cotton in the bloom and later stages than in the pre-bloom stage of growth. |
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The Texas A&M
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A
report of heavy greenbug feeding in a sorghum field was received this
week. The plant growth stage was booting and the damage was reported to
be the loss of more than one whole leaf per plant. Corn leaf aphids and
yellow sugarcane aphids were also reported from the same field. However,
the damage symptoms were reported to be deep red-colored (fired) leaves
which were dying. Greenbugs are a light green aphid with a dark stripe
running the down the middle of their backs. Corn leaf aphids are darker
green to almost black and have no stripe down their backs. Yellow sugarcane
aphids are lemon yellow and often found near the bottom part of the plant.
Generally, yellow sugarcane aphids are pests on very young sorghum plants
and typically do little damage to older sorghum The threshold for greenbugs
in sorghum varies with the size (age) of the plant. The enclosed table
from the Texas Agricultural 
