<Li> The chestnut weevil (Curculio elephas) most often damages the fruits . In Hungary, it swarms in chestnut orchards around August 20, particularly strongly around noon and in sunny weather . The eggs are laid into the cupules or around the peduncle joints . The larvae feed on the nuts and leave only nutchips and excrement within . While the chestnuts ripen, the larvae retreat into the ground after having chewed their way out of the nuts . The following July, they turn into pupae . The larvae of the chestnut weevil can only chew their way out of a fallen nut, so breeding occurs mostly where chestnuts lie on the ground for a sufficient length of time, or where the trees produce many small fruits which remain behind at the harvest . Timing the harvests to pick up the chestnuts as soon as they fall reduces the numbers of the overwintering larvae . Regular soil work is also unfavourable to its life habits . Small grafts are sprayed with chemicals . A warm aerosol - based protection has been developed for older trees, by Sifter and Bürgés in 1971 . It is not recommended to plant chestnut orchards beside Turkey oak forests, because both trees are susceptible to the chestnut weevil (which also uses the Turkey oak acorn to develop), and the Turkey oak trees can pass it on to the chestnut trees . </Li> <Li> In Hungary, the most common moth threatening chestnut trees is the acorn moth (Laspeyreisa splendana) and its subspecies . Its grayish - yellow larvae cause similar damage to that of the chestnut weevil, but they spin characteristic webs among the nutchips and larval excrement . This moth causes about 5--41% of the damage that occurs in western Hungary's plantations . Plantations need regular protection against these moths, the occurrence of which does not decrease . </Li> <Li> In New Zealand, the grass grub beetle eats the soft new - season foliage . They can entirely strip a young tree in the late spring, when they fly at dusk, often in huge numbers . </Li> <Ul> <Li> Chestnut blight fungus (Cryphonectria parasitica) (formerly Endothia parasitica) affects chestnut trees . The Eastern Asian species have coevolved with this disease and are moderately to very resistant to it, while the European and North American species, not having been exposed to it in the past, have little or no resistance . Early in the 20th century, chestnut blight destroyed about four billion American chestnut trees, and reduced the most important tree throughout the East Coast to an insignificant presence . The American chinkapins are also very susceptible to chestnut blight . The European and West Asian chestnuts are susceptible, but less so than the American species . The resistant species (particularly Japanese and Chinese chestnut, but also Seguin's chestnut and Henry's chestnut) have been used in breeding programs in the U.S. to create hybrids with the American chestnut that are also disease - resistant . The bark miner Spulerina simploniella (Lepidoptera: Gracilariidae) was found in intensively managed chestnut coppices in Greece, but not in orchards . The larvae (and the rain) may be agents in the spread of the disease . They mine under the thin periderm of young trees up to 10 years old, while the stem bark is still smooth . Rain during the pupation period (around the last week of May and first two weeks of June), and the actions of the larvae, may collude for conidiospores to come into contact with the freshly exposed phloem, and thus cause cankers . </Li> <Li> Ink disease also appears in a number of other plants . The disease attacks the phloem tissue and the cambium of the roots and root collars about 10--20 cm above ground . Wet rot settles in as a result . It was named after the ink - black color of the tannic acid becoming (oxidized) after seeping out, but that symptom is not a characteristic of only that disease . The same ink - black color can appear following other types of decays and mechanical injuries that make liquids seep through; these liquids can also oxidize after contact with air . Moreover, with some phytophthoric diseases, no tannic acid is generated . With the ink disease, the leaves turn yellow and later fall off; the fruits remain small, and the nuts prematurely drop out of the burrs . These dry and remain on the trees throughout winter . In acute cases, root decay makes the trees dry out and wither away . It is caused by Phytophthora cambivora and Phytophthora cinnamomi . </Li> <Li> Phytophthora disease is the longest - known chestnut tree disease leading to tree death . Of the two main pathogens for this disease, the one in European chestnuts is known since 1971 to be Phytophthora cambivora . Phytophthora cinnamoni was discovered in chestnut trees in the United States in 1932 . Both trigger similar symptoms . Since then, it has also been shown to occur in most European chestnut - growing countries . It is difficult to differentiate between the two pathogens . Chemicals seem of little effectiveness . Many countries impose strict prophylactic rules to prevent the spread of the disease . </Li> <Li> Melanconis modonia can infect trees through injuries and induce "bark death". It was first reported in Hungary by Hausz in 1972 . The damage is of little consequence in older or stronger trees, but it affects sapling graftings in nurseries . Coryneum perniciosum, one of the two conidium - like side forms of this fungus, occurs on all decayed, ligneous parts of a chestnut tree . The symptoms of infection on young smooth trunks is similar to that of the chestnut blight fungus Cryphonectria . For this reason, it has persistently been wrongly thought of as the pathogen for ink disease . With Melanconis, the bark sinks in and takes on brownish - red tones, with black lentil - like multicell conidium bodies and black cone - like stromas breaking through the bark . But unlike with Cryphonectria, there are no orange - colored fruiting bodies . Prevention primarily includes keeping the tree in good shape; some further protections against Cryphonectria also help prevent bark death caused by Melanconis . </Li> <Li> Chestnut mosaic virus is probably transmitted by the oak aphid Myzocallis castanicola . </Li> <Li> Root rot is caused by the honey fungus Armillaria mellia . When planting Castanea, recently cleared land is best avoided to help resist this fungus . The disease is more prevalent on heavier and poorly drained soil types . </Li> <Li> Leaf spot is the most common disease for chestnut trees (Mycosphaerella maculiformis). It is known as cylindrosporium leaf spot disease, after its summer conidium form Cylindrosporium castaneae . The pathogens spend the winter in the white spots of the fallen leaves . At spring time, it reinfects the new leaves . In or near June, tiny white spots on the leaves appear, which grow and turn brown over time . At the end of the summer, the spots entirely cover the leaf, which turns yellow . In rainy and humid weather with large temperature fluctuation, the tree loses its leaves . If August is dry and warm, the infected leaves roll up, the arteries twist, and the dead leaves dry on the tree until defoliage . This recurs yearly, though the extent of the damage varies from year to year . Some species are more resistant than others . </Li> <Li> Oak mildew is among several foliage diseases of smaller significance for European chestnut growing . It infects the most trees (Microsphaera alphitoides). Younger trees suffer most; their shoots become short - jointed, growth is delayed, and they develop sensitivity to frostbite . In older trees, the fungus usually infects only the tip of the shoots . The pathogens hibernate in the shoots and infect the leaves from there . The fungus grows on the top of the leaves, with the appearance of a coating only in midsummer . The infected leaves' development slows down or stops, the distance between their vessels shrinks, and the vessels themselves become curly . </Li> <Li> In storage rot, breaking the tuft provides the most common entrance for fungal spores during storage . Cyboria, the most diffuse, turns the flesh black and spongy . Other fungi are known, such as Rhizopus, Fusarium, and Collectotrichum . </Li> </Ul>

What does a fresh water chestnut look like