Tech Notes Issue 21

African Black Beetle Grubs Developing

The African black beetle (Heteronychus arator) females began laying eggs around the first week in September and will continue through late December. October is when peak egg laying occurs. Egg hatching occurs from late September through middle of November. The peak larvae and pupae occurs from middle of November through December.

The larvae go through multiple instars with the 3rd instar (December through January) being the most damaging. The grubs feed on the roots of bentgrass and couchgrass plants.

Summer Greens Management: Effect of cultural practices on anthracnose

In the previous issue of Tech- Notes-SH the impact of topdressing creeping bentgrass/ Poa annua greens on anthracnose incidence was discussed. As a follow-up the impact of nitrogen fertilization, verticutting, and plant growth regulators on putting greens health is investigated.

Nitrogen fertility, either to little or too much, influences the severity of most turfgrass diseases. Regarding anthracnose, itrogen deficiencies can enhance anthracnose. Researchers at Rutgers University found that the greatest effect in reducing anthracnose outside of raising the height of cut was nitrogen fertilization (1). They found that applying low rates of soluble nitrogen (4.9 kg ha^-1) on a 7-day schedule starting in late spring through summer had the most consistent and greatest impact on reducing anthracnose. This included treatments where the same amount of nitrogen applied on a 28-day schedule.

Verticutting (3 mm) or grooming of the turf canopy once every 2-week had no effect on anthracnose severity (1). Plant growth regulator (PRIMO MAXX®) applied on a 14-day schedule from late spring through summer had inconsistent effects on anthracnose but did not aggravate the disease severity (1). However, applied in combination with the 7-day low rate nitrogen treatments had the greatest impact on reducing disease severity.

 References

1. Inguagiato, J.C. J.A. Murphy, and B.B. Clarke. 2008. Anthracnose severity on annual bluegrass influenced by nitrogen fertilization, growth regulators, and verticutting. Crop Science 48:1595-1607.

Photograph: Recent published research out of Rutgers University has found no effect of topdressing,

 verticutting, or brushing on anthracnose severity.