30.0 T 



"- 20.0 ■- 



5 15. 0-- 



£ 10.0 -- 



0) 



u 

 o 



Q. 



5.0 -- 

 0.0 



No fungicide applied 

 Fungicide applied 



4- 



1 1 — 



20 40 60 



Distance from Border (meters) 



80 



Figure 5. Effects of distance from the block border on flyspeck incidence in fungicide-sprayed 

 and non-sprayed apples. 



the swath were sampled for flyspeck. Sprayed trees 

 at the same distances in the block were also sampled 

 for flyspeck. Again, the closer the trees were to the 

 border, the more flyspeck there was (Figure 5). 

 Fungicide applications greatly decreased flyspeck 

 incidence at any distance, largely removing the dis- 

 tance effect in all of the plots. In the strip plots 

 without summer fungicides, flyspeck incidence 

 dropped from 25% to 16% over the first 20 meters 

 from the border. However, there was little decrease 

 over the next 60 meters. Similarly, in the small 

 plots from up to 90 meters without fungicides, 

 flyspeck incidence was relatively high, around 12 

 to 16%. However, in the plots beyond 90 meters 

 from the border, flyspeck dropped to about 6%. 



We know that in the absence of fungicides, fly- 

 speck can vary dramatically, from barely existing 



in some blocks to infesting nearly one third of the 

 fruit in another. In orchards where natural occur- 

 rence of flyspeck is very low, it is tempting to say 

 that summer fungicides are not needed, or may be 

 effective with only a single application. In this ex- 

 periment, we saw that the combined factors (date, 

 relative altitude of the block, slope, density of 

 brambles in the border, canopy density, and dis- 

 tance from the border) could explain about 30% of 

 the differences in flyspeck incidence we saw that in 

 the no fungicide blocks. That means that some 

 other, as yet unidentified, factors are having a ma- 

 jor effect on flyspeck. If we can identify these fac- 

 tors, it will be possible to determine which blocks 

 need normal summer fungicide treatments, and 

 which may produce a high quality crop with few or 

 no summer fungicides. 



»T> *T# %Xa *X* *^ 

 •^ •^ •^ •^ *^ 



Fruit Notes, Spring, 1996 



