Moses now explains the nature of the curses.
They will be cursed by disease (vs21-22). What is particularly interesting about verse 22 is that Moses: ‘lists seven afflictions that will hit Israel’ a number that in: ‘Hebrew symbolises totality and finality’[1] such would be the serious nature of these offences. Drought is indicated in verses 23-24. Verses 25-26 give an interesting reversal on the subject of foreign 
military aggression as described originally in verse 7. Whereas the defeat of their enemies would be seen as completely overwhelming, in the case of the curse their enemies would overwhelm them (as emphasised again by the number seven, in each case representing complete victory or complete defeat). Diseases make a reappearance in verses 27-28 with an interesting reference to the kind of diseases that were found in Egypt (some scholars see a reference to the plagues of Egypt here in the symptoms that are described) perhaps indicating that disobedience to the Lord’s commands was a route back to a kind of slavery! Military aggression against Israel is the feature of verses 36-34 with Israel’s domestic livelihood being thrown into confusion and disarray by an invading army. Israel will be defenceless, and all the slaughter and brutality of the invading troops will lead to madness! Another dose of disease follows in verse 35 and then there is a return to the results of invasion. Verses 36-37 threaten the exile that Israel would experience in the future and plainly states that as a nation they will become a national joke due to their disobedience!
There is a persuasive argument that these judgements could be seen as the punishment fitting the crime for lack of obedience. As we have seen in the previous chapters there had been continual warnings about the danger of worshipping the gods of the Land. Predominant among these gods was Baal who was worshipped by the Canaanites as the 
deity who provided the harvest and was also seen as the god of fertility who gave children. Finally, Baal was seen as the God of War and, as a mighty warrior as he was supposed to defend those who worshipped him. What better punishment for the worship of a false god like Baal than complete failure in all the areas that he was supposed to have an influence in! A case from Israel’s history of God making the punishment fit the crime was when Israel turned to the worship of Baal under the kingship of Ahab influenced by his wife Jezebel. At that time God withheld the rain making a mockery of Baal’s supposed provision of the harvest and raised up the prophet Elijah as His spokesman (1 Kings 17:1).[2]
In verses 38-42 there is a repeat of the curses concerned with agriculture, coupled with the threat of exile in which they will lose their sons and daughters. The section ends with the threat of swarms of insects devastating the land.
What is interesting is although we have seen these curses before, the emphasis here is on the people not benefiting from the wonderful land that the Lord was giving them. Here is a lesson for us today, how often we miss out on the blessings that God would give us because of lack of faith, trust and our disobedience. Verses 43-44 in this section show interesting reversal concerning foreigners (aliens) that would live among them. The picture that has been constant in Deuteronomy is that ‘the alien’ needs to be provided for 
as they were classed among the weak and vulnerable in society. But here is a picture of them being in a position of positive advantage or authority
This section ends with a reversal of what the Lord had decreed concerning the lending of money. In verse 12 of this chapter, the picture was of God blessing the nation through plentiful harvests which would provide great prosperity so that they lent to other nations but did not have to borrow from them. Here in verse 44 this has been turned upside down and the promise of verse 13 has also been reversed, Israel would not be a leader it would be a follower! Surely, this can be taken as a warning to Christians today not to deviate from God’s Word as they will end up losing the blessings that are found within it!
[1] John D Currid, Deuteronomy, an EP study commentary (Evangelical Press, Darlington, 2006) 438.
[2] I am indebted to Raymond Brown and his excellent commentary on Deuteronomy for this observation of the punishment fitting the crime. Raymond Brown, The Message of Deuteronomy, The Bible Speaks Today (Inter-Varsity-Press, 1993) 270.