Production Practices and Quality Assessment of Food Crops. Vol. 1

152 S. Pereira-Lorenzo and A. M. Ramos-Cabrer
Efforts have been made to detect ink disease spread in chestnut using aerial
photography (Martins et al., 1999).
Some works studied the level of resistance of Castanea spp. to the ink disease
(Guedes-Lafargue and Salesses, 1999; Fernandez-Lopez et al., 2002).
Phosphite, the anionic form of phosphonic acid (HPO 3) –2 induce strong and
rapid defense responses in plants infected by P. cinnamomi and it is being trial as
a foliar applicant or injected into trees (Hardy et al., 2001).
The main origin of resistance to blight is coming from Asiatic species, mainly
C. mollissima (Hebard and Stiles, 1996). Two or three genes probably control
resistance in the Chinese species, and they are only partial dominant. American
Chestnut Foundation has developed a backcross-breeding program to restore the
American chestnut C. dentata. By the third backcross it is getting progeny on average
15/16 American, which eventually exhibit entirely American characteristics in later
generations.
10.1. Harvesting
10. MARKET AND PROCESSING
Harvesting is the hardest and costly work in chestnut since it is made by hand in
most orchards. Some alternatives have been proposed but it has been used only in
few occasions.
Owners, normally with the help of the family or friends collect chestnut production.
Large orchards contract gangs paid on daily basis and only harvesting
biggest nuts can be profitable.
Different methods have been suggested to improve chestnut harvesting such as
vacuums, brushes and nets.
A good preparation of the ground is necessary to allow accessibility for machines.
The main problem with vacuums and brushes are the big quantity of burs, leaves
and pebbles collected that must be discarded later. Some traditional machinery has
been developed (Figure 25). An additional problem it is that when chestnuts are
mixed with soil this can be the increase level of diseases associated with conservation.
Most interesting appear to be the system proposed by Frenchs, installing nets
under the trees elevated from the ground with sticks (Breisch, 1995). This is expensive
and time consuming, but the sanitary status will be excellent.
When nuts are harvested by machines or in some humid areas where nuts do
not fall from bur, it is necessary to isolate them. Some machines have been developed
to do that. Traditionally, nuts into burs are accumulated in small constructions
(Figure 26) or in heaps (Figure 27) in the orchard area. After some weeks, burs begin
to rot and then it is easier to collect the nuts.