orange_orig data frame
   variety pesticide yield
1        1         1    49
2        1         1    39
3        1         2    50
4        1         2    55
5        1         3    43
6        1         3    38
7        1         4    43
8        1         4    58
9        2         1    55
10       2         1    41
11       2         2    67
12       2         2    58
13       2         3    53
14       2         3    42
15       2         4    85
16       2         4    73
17       3         1    66
18       3         1    68
19       3         2    85
20       3         2    92
21       3         3    69
22       3         3    62
23       3         4    85
24       3         4    89

Call:
lm(formula = yield ~ variety + pesticide)

Residuals:
     Min       1Q   Median       3Q      Max 
-15.0000  -3.2604   0.9167   2.8750  14.6250 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept)   38.833      3.674  10.570 3.78e-09 ***
variety2      12.375      3.674   3.368 0.003424 ** 
variety3      30.125      3.674   8.199 1.72e-07 ***
pesticide2    14.833      4.242   3.496 0.002577 ** 
pesticide3    -1.833      4.242  -0.432 0.670773    
pesticide4    19.167      4.242   4.518 0.000266 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 7.348 on 18 degrees of freedom
Multiple R-squared: 0.8535,	Adjusted R-squared: 0.8128 
F-statistic: 20.97 on 5 and 18 DF,  p-value: 6.213e-07 


Call:
lm(formula = yield ~ variety + pesticide + variety * pesticide)

Residuals:
   Min     1Q Median     3Q    Max 
 -7.50  -3.75   0.00   3.75   7.50 

Coefficients:
                    Estimate Std. Error t value Pr(>|t|)    
(Intercept)           44.000      4.644   9.476 6.39e-07 ***
variety2               4.000      6.567   0.609  0.55381    
variety3              23.000      6.567   3.502  0.00436 ** 
pesticide2             8.500      6.567   1.294  0.21990    
pesticide3            -3.500      6.567  -0.533  0.60378    
pesticide4             6.500      6.567   0.990  0.34181    
variety2:pesticide2    6.000      9.287   0.646  0.53040    
variety3:pesticide2   13.000      9.287   1.400  0.18689    
variety2:pesticide3    3.000      9.287   0.323  0.75223    
variety3:pesticide3    2.000      9.287   0.215  0.83311    
variety2:pesticide4   24.500      9.287   2.638  0.02165 *  
variety3:pesticide4   13.500      9.287   1.454  0.17170    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 6.567 on 12 degrees of freedom
Multiple R-squared: 0.922,	Adjusted R-squared: 0.8505 
F-statistic: 12.89 on 11 and 12 DF,  p-value: 5.22e-05 

ANOVA table for additive model:
Call:
   aov(formula = yield ~ variety + pesticide)

Terms:
                 variety pesticide Residuals
Sum of Squares  3668.583  1992.458   971.917
Deg. of Freedom        2         3        18

Residual standard error: 7.348154 
Estimated effects may be unbalanced
ANOVA table for model with interaction:
Call:
   aov(formula = yield ~ variety + pesticide + variety * pesticide)

Terms:
                 variety pesticide variety:pesticide Residuals
Sum of Squares  3668.583  1992.458           454.417   517.500
Deg. of Freedom        2         3                 6        12

Residual standard error: 6.566963 
Estimated effects may be unbalanced