Plums in the Home Orchard
By: Jonathan Sturm
There are two sorts of plums, Prunus domestica (European plums) and P. Salicina (Japanese plums, though they are actually from China). European plums have smaller fruit than their Asian counterparts, have drier flesh and have a more aromatic taste. Many have a high enough sugar content to be dried without the necessity to take out the stone (seed). There are two sorts, yellow skinned, called Greengages and blue. They make excellent jams, wines, preserves and desserts.
Japanese plums are large, vigorous trees bearing large, juicy fruit. They come in red, purple and yellow skinned varieties with yellow flesh, though there is a sub-group of red-fleshed plums called "blood plums". Having a shorter chilling requirement than European plums, they flower somewhat earlier and are thus more suited to warmer districts.
Plums grow well on a wide range of soils and do not mind heavy soils. They have very similar requirements to apples and grow well wherever apples are common. Watering is required to enable the fruit to achieve a good size, particularly the European types.
Japanese plums set fruit on last year's wood and European plums on two-year-old wood. For optimum fruit set, cross-pollination is essential for most varieties. Due to their different flowering times, Japanese plums are unsuitable as cross pollinators for European plums. Some varieties drop fruit due to poor pollination. Fruit set is improved by spraying with a 20% sugar solution to encourage more assiduous bee activity. The European plum Angelina Burdett is an example of this kind.
Most Japanese and some European plums need fruit thinning to obtain sufficient fruit size. As a general rule, if fruit buds outnumber leaf buds, then thinning will be required. Thin to a spacing of 7-10 cm apart for Japanese and 5-8 cm for European plums.
Japanese plums are very vigorous trees and require hard pruning. They are generally grown as a vase with 6-9 main leaders. Prune the leaders back to a quarter of their length, leaving the laterals unpruned. Shorten the laterals of heavy bearing varieties to reduce the amount of hand thinning required. Renew the bearing laterals after they have fruited a second time. The more vigorous varieties should have unwanted laterals removed around midsummer.
Other than defining the leaders, European plums require little pruning. Shorten laterals longer than about 50 cm and thin any crowded spurs. New South Wales growers say that yields are improved by pruning plums every other year. Due to the incidence of silver leaf disease (a fungal infection that enters the tree through wounds), do not prune plums in wet weather.
Plums do not ripen simultaneously, so they should be harvested as they ripen. They are at their best when fully ripe.
The larva of the sawfly, pear and cherry slug can be a pest. It is a black, slimy beast, up to 1 cm long. The leaves of the tree are skeletonised, and in a severe infestation, the tree suffers badly. For the home gardener, dusting the tree with fine sand, sifted wood ashes or finely ground limestone is easiest and has the advantage of not killing desirable orchard biota. On a large scale, pyrethrum works very well, and despite killing predatory insects, does break down rapidly.
Brown rot can affect the fruit, and pre-blossom sprays of Bordeaux, or other copper based fungicide is recommended where this is a problem. Lime sulphur, or waterglass sprays may be necessary to follow up.
European Plums Varieties
|1. Coe's Golden Drop||5,3,12,16||Excellent flavour. Good for drying. Late season.|
|2. Cole's Golden Gage||3,12,16||Good flavour. Mid late season.|
|3. Greengage||1,6,11||Good flavour. Biennial bearing. Tend to ripen unevenly. Mid season.|
|4. Jefferson||5,7,9,10,12||Excellent flavour. Good cropper. Mid early season.|
|5. Reine-Claude de Bavay||4,10,*||Hard to obtain, but the flavour is excellent. Matures mid to late season.|
|Blue Plums||Cross Pollinator||Comments|
|6. Angelina Burdett||7,9,10,11,12||Very good quality. Needs more thinning than most. Early mid season.|
|7. Black Diamond||5,6,9,11,12||Jam plum. Large fruit, but poor flavour. Early mid season.|
|8. Damson||*||Small, sour fruit. Suit cooking and jam only.|
|9. Early Orleans||4,6,11,12||Good jam plum. Excellent flavour. Early season.|
|10. Grand Duke||4,6,7,11,12||Heavy cropper. Tree too big for small gardens. Mid late season.|
|11. King Billy||6,9,10,12||Heavy bearer. Mediocre flavour. Early mid season.|
|12. President||4,6,10,16||Juicy, good quality fruit. Can be cool stored for up to 3 weeks. Mid late season.|
|15. Giant Prune||1 1,3,16,17||?|
|16. Prune d'Agen||1,3,15,17,*||Main prune plum. Good pollinator. Very late season.|
|17. Robe de Sergeant||1,3,15,16||?|
|Japanese Plums Yellow Flesh||Cross Pollinator||Comments|
|18. Burbank||22,27||Good eating. Fruit splits. Needs thinning. Mid early season.|
|19. Doris Fisher||29||Jam plum with tough skin. Mid late season.|
|20. Formosa||21,23,33||Good flavour. Good for jam. Mid early season.|
|21. Narrabeen||23,29,33||Sweet and juicy. Mid late season.|
|22. October Purple||27||Sweet and juicy. Prone to sunburn. Mid late season.|
|23. Santa Rosa||21,27,29,*||Juicy and excellent flavour. Early.|
|24. Shiro||21,23||Bland, but juicy. Early.|
|25. Shipper||23,24,33||Firm, good flavour. Prone to sunburn. Late season.|
|26. Thiele's Late||?||Very good flavour. Suits warmer districts. Very late season.|
|27. Wickson||22,23||High quality. Needs thinning. Mid early season.|
|28. Wilson's Early||23,*||Thorny, vigorous, mediocre flavour. Not for jam. Very early.|
|Blood Plums||Cross Pollinator||Comments|
|29. Mariposa||20,21,32,33||Juicy and good flavour. Splits and drops fruit pre-harvest. Mid season.|
|30. Omega||23,29||Firm. Good eating. Late season.|
|31. Red Ace||23,28||Excellent flavour, prone to drop fruit. Late season.|
|32. Ruby Blood||20,21,29,33||Very firm. Stores and carries well. Very late season.|
|33. Satsuma||20,23,21,29,32,*||Good flavour. Good jam plum and for stewing. Prone to brown rot. Mid season.|
|34. Trenwell||?||Good eating and jam. Splits when ripe. Late season.|
* = self fertile
? = not known