Overlapping of Life Cycles with Heat and Moisture Stress is Upon Us

June brought a lot of rainfall for the Mid-Atlantic region. There were a number of golf courses in the Washington, D.C., Baltimore and Philadelphia corridor that recorded more than 12 inches of rainfall from June 2 through July 15, with some as high as 18 inches. The warm weather we are currently experiencing is a big change from the summer of 2014. Abiotic issues like wet wilt and heat stress were present at many of the golf courses I visited.

Although annual bluegrass weevil (ABW) damage was lower than normal during that time frame, it was likely masked by adequate or above-adequate moisture. The peak damage from the second round of weevil larvae occurred between July 10 and July 20, and this coincided with some drier days with wilt occurring. In most of the scenarios, I was able to find all life stages present in the damaged areas (larvae, callow adults, pupae and true adults).

This week I received a phone call from a superintendent about an anthracnose outbreak on a number of pocketed greens in the historically wetter areas. He wanted to have some plugs looked at for a diagnosis because they had applied a strong tank mix for anthracnose a few days prior to the suspected outbreak. Upon inspection of the plugs, I did not find any fungal pathogens present in the foliage, so I broke the plugs apart to examine the roots for pathogens. Upon examination, I found that there were late instar ABW larvae and pupae present. He had applied an insecticide targeting larvae on June 15, but nothing since then (about 6 weeks prior). So, we put a game plan together for curative control of ABW. The superintendent was very surprised that the weevils were causing damage to greens, and said, "I have been managing this bug for a long time and never seen it damage a green.” In my opinion (I don't have any data on this), mowing and rolling tends to kill, injure or scare a lot of adults on the putting green surface. Hence, the reason we typically see higher pressure on the collars. During wet and hot periods, if you are backing off of mowing and rolling, you may see more ABW activity on greens.

Something else I observed this June was a drainage basin containing hundreds of ABW adults floating in rain water. The superintendent that had a damage outbreak on a few wetter areas of greens said that water will collect in the exact same pattern as the damage. This may deposit adults in these areas. Therefore, here are a few lessons from this week:

1. If you are backing off of mowing and rolling, which is suggested to reduce mechanical stress during the heat, be sure to scout for ABW.
2. During periods of heavy rainfall where surface water is moving across the turf, the best place to scout for adults is likely where water collects.

From this point forward, control options for ABW may be responsive with an insecticide targeting larvae. During warm weather the pyrethroids  tend not to work as well. The organophosphates targeting adults can be useful, but many have a negative perception due to the odors.

Overlapping of Life Cycles with Heat and Moisture Stress is Upon Us

June brought a lot of rainfall for the Mid-Atlantic region. There were a number of golf courses in the Washington, D.C., Baltimore and Philadelphia corridor that recorded more than 12 inches of rainfall from June 2 through July 15, with some as high as 18 inches. The warm weather we are currently experiencing is a big change from the summer of 2014. Abiotic issues like wet wilt and heat stress were present at many of the golf courses I visited.

Although annual bluegrass weevil (ABW) damage was lower than normal during that time frame, it was likely masked by adequate or above-adequate moisture. The peak damage from the second round of weevil larvae occurred between July 10 and July 20, and this coincided with some drier days with wilt occurring. In most of the scenarios, I was able to find all life stages present in the damaged areas (larvae, callow adults, pupae and true adults).

This week I received a phone call from a superintendent about an anthracnose outbreak on a number of pocketed greens in the historically wetter areas. He wanted to have some plugs looked at for a diagnosis because they had applied a strong tank mix for anthracnose a few days prior to the suspected outbreak. Upon inspection of the plugs, I did not find any fungal pathogens present in the foliage, so I broke the plugs apart to examine the roots for pathogens. Upon examination, I found that there were late instar ABW larvae and pupae present. He had applied an insecticide targeting larvae on June 15, but nothing since then (about 6 weeks prior). So, we put a game plan together for curative control of ABW. The superintendent was very surprised that the weevils were causing damage to greens, and said, "I have been managing this bug for a long time and never seen it damage a green.” In my opinion (I don't have any data on this), mowing and rolling tends to kill, injure or scare a lot of adults on the putting green surface. Hence, the reason we typically see higher pressure on the collars. During wet and hot periods, if you are backing off of mowing and rolling, you may see more ABW activity on greens.

Something else I observed this June was a drainage basin containing hundreds of ABW adults floating in rain water. The superintendent that had a damage outbreak on a few wetter areas of greens said that water will collect in the exact same pattern as the damage. This may deposit adults in these areas. Therefore, here are a few lessons from this week:

1. If you are backing off of mowing and rolling, which is suggested to reduce mechanical stress during the heat, be sure to scout for ABW.
2. During periods of heavy rainfall where surface water is moving across the turf, the best place to scout for adults is likely where water collects.

From this point forward, control options for ABW may be responsive with an insecticide targeting larvae. During warm weather the pyrethroids  tend not to work as well. The organophosphates targeting adults can be useful, but many have a negative perception due to the odors.