Anthraquinone is a chemical compound which is used to treat seeds before planting to prevent bird predation.
Avery et al. (1998) evaluated the effect of 1 % anthraquinone treatment (380ml AQ50, 1120ml water, 2.4 ml Exhalt 800) on rice sprout density at two sites in Louisiana, USA. The risk of crop damage from red-winged blackbird (Agelaius phoeniceus), brown-headed cowbirds (Molothrus ater), and boat-tailed grackles (Quiscalus major) was reduced in treatment plots at both sites (RR = 0.36 and RR = 0) compared to control plots. Another Louisianian study (Cummings et al. 2002) found Flight Control ™ (2%) to reduce the impact of blackbird (Icterinae) losses of rice seeds (RR = 0.31).
Cummings et al. (2002b) conducted two field tests. In the first test, rice seed surface was coated with 2% Flight Control ® (g/g) and 0.3% Exhalt ® sticker (g/g), and blackbirds consumed significantly less seeds from the treated than untreated lanes (RR = 0.13). In the second trial, rice seeds were water soaked and coated with Flight Control ™ (2%). Blackbird consumption was monitored over 7 days, and while the untreated seeds were completely consumed after 3 days, losses of treated seeds did not increase during the observation time (3 days RR = 0.03, 5 days RR = 0.03, 7 days RR = 0.03). An Irish study also found that when wheat was treated with Morkit (Anthraquinone 25) at 2.25l/t to prevent rook (Corvus frugilegus L) damage, treated blocks had higher plant density in two subsequent years (49 % higher and 94 % higher respectively).
The effect is, however, not entirely conclusive between studies particularly when evaluating the impact on yield. A study from New York state (Curtis et al. 2019) found that the silage yield, was no different between fields where corn were treated with Avipel Shield was used to prevent losses to birds, compared to control fields (0 %). Similarly, Kaisler et al. (2021) found in their North Dakota study that sunflower fields treated with Avipel™ (50% anthraquinone) had 5 % lower yields than untreated controls, when there was low bird pressure on the crops. In South Dakota, Werner et al. (2019) sought to prevent Canada goose (Branta canadensis) damage on soybean by treating the crop with 9.4 L Flight Control ® Plus goose repellent/ha (active ingredient: 50% 9,10-anthraquinone). Yields were lower in treated plots than in controls, but yield differences varied with distance to wetland and plant emergence level (-51 % to 4 %).
