Tank Mixing Insecticides:
A novel NO-OP program approach is shown in Fig. 6. This approach takes advantage of our knowledge of CM biology and insecticide mode-of-action to combine two products as a tank mix in one application. Oil is used in the prebloom program for control of scale and suppression of mites and aphids, and Success is applied at petal fall for LR control. Oil (1% v/v) is again applied at 200 CM degree-days, or 50 degree-days before expected CM egg hatch. The oil kills many of the eggs deposited up to this point. A tank mix of a larvicide (Assail or Calypso) and an ovicide (Rimon or Intrepid) is applied as a delayed first cover treatment at 350 degree-days, or 100 degree-days later than the normal egg hatch timing (Fig. 6). No other first-generation treatments are used for CM control. The second-generation treatments could be either Intrepid or Rimon, whichever was NOT used in the tank mix application, or if CM densities were low enough and no LR problems were expected a CM virus product could be used.
| Fig. 6 |
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How does the mixing of two insecticides with different modes-of-action work when applied only one time per CM generation? A key element to this program is the use of oil at 200 degree-days. This treatment kills the eggs that had been laid down between the beginning of CM flight (= Biofix) and this point (#1 - Fig. 7). Killing these early eggs delays the beginning of significant egg hatch and makes it possible to delay the tank mix application until 350 degree-days. At 350 degree-days, some CM eggs would be hatching, but the larvicide (Assail or Calypso) would kill the small larvae as they attempted to enter fruit (#2 - Fig. 7). The ovicide (Rimon or Intrepid) kills eggs that the oil missed but had not yet hatched or deposited after the oil treatment (between 200 and 350 degree-days, #3 - Fig. 7). In other words, these products have “kick back” activity to kill eggs the oil treatment missed. In addition, the ovicide kills eggs laid down after it is applied (#4 - Fig. 7), thus, eggs that would have hatched after the residue of the larvicide ran out (#5 - Fig. 7) are already dead. By delaying the tank mix application until 350 degree-days the residual activity of both the ovicide and larvicide provides control during the most active period of the CM generation and therefore provides protection for the entire generation. This approach could also be repeated in the second generation, but it would be better to switch to softer controls at this time and conserve the new products as much as possible. This approach can work with the different combinations shown in Fig. 7, even using an OP insecticide as a larvicide, but this would defeat the purpose of a NO-OP program.
We have several years of experience testing these kinds of tank mix programs (Fig. 7) under extreme CM pressures. Table 5 provides examples of the percent reduction of CM injury achieved by the different tank mix programs. Most of the tank mix programs provided very good suppression of fruit injury, in some cases similar to that of a standard OP-based program (Guthion). A combination of Rimon with either Assail or Calypso proved to be especially effective. This table also shows that even very soft programs that included just Intrepid or combined treatments of CM virus (Cyd-X) and Intrepid can provide good suppression of CM injury. These latter programs combined with CM MD could be expected to provide very good control where pressures were low to moderate.
| Fig. 7 |
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Table 5. Level of CM fruit injury suppression achieved by different mode-of-action tank mix programs compared to a typical sequential application of treatments
Tank mix program
|
Efficacy (percent reduction
in fruit injury relative to an untreated control)
|
| Oil @ 200DD; Calypso + Intrepid @ 350DD | 88.3
|
| Oil @ 200DD; Calypso + Rimon @ 350DD | 99.7
|
| Oil @ 200DD; Assail + Rimon @ 350DD | 98.6
|
| Oil @ 200DD; Assail + Intrepid @ 350DD | 95.0
|
| Oil @ 200DD; Intrepid; Intrepid * | 74.7
|
| Oil @ 200DD; Cyd-X; Intrepid * | 60.3
|
| Guthion; Guthion * | 98.7
|
| Assail; Assail * | 94.1
|
* program without tank mix modes-of-action